Sid Meier's Civilization V

Sid Meier's Civilization V

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Zigzagzigal's Guide to Byzantium (BNW)
By Zigzagzigal
Byzantium's strength is in its flexibility, being able to use their unique ability to fit the game's situation. As such, they can make unpredictable opponents. This guide goes into plenty of detail about Byzantine (Byzantine as in of Byzantium, not as in excessively complicated) strategies, uniques and how to play against them.
   
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Introduction
Note: This guide assumes you have all game-altering DLC and expansion packs (all Civ packs, Wonders of the Ancient World, Gods & Kings and Brave New World)



The Roman Empire at its height was the world's largest and most powerful empire, but the relentless desire for expansionism would stretch classical-era infrastructure to its limits. Starting in the late 3rd century of the common era, the role of the Emperor would be shared between various individuals which would only serve to divide the empire. The east empire - the Byzantine empire - had wealth and diplomatic skills to fend off invaders in the 5th century such as the Huns; the west did not. Come the early sixth century, Justinian I would secure the eastern frontier of the empire with tributes to the Persians, while his consort Theodora would convince him to stay in the city in face of riots. With this greater stability, the Byzantine empire could expand west, to dominate the Mediterranean like Rome of old once did.

Now, clever diplomacy and economic strengths are virtues you must live up to as leader of Byzantium, avoiding the mistakes of Justinian I's successor, Justin II, who stopped paying tribute to Persia and lost much of the land Justinian I had taken in Italy. By the 7th century, the empire had to see off the Persians, but the wars had left them both vulnerable to raids from the new Arabian Empire. While the Macedonian Dynasty from the 9th to 11th centuries would form a new golden age, just 29 years after the dynasty's end, the Christian church underwent a great schism, leaving Byzantium isolated from western Europe. Eventually, this would lead to the Fourth Crusade at the beginning of the 12th century, where western Christian forces ended up sacking Constantinople, ruining the remnants of the empire's ability to defend itself. The city would finally fall to a new force from the east - the Ottomans. This decline is something you must avoid as leader. Build on the virtues of Byzantium's flexibility and longevity. Build a civilization which will stand the test of time.



Before I go into depth with this guide, here's an explanation of some terminology I'll be using throughout for the sake of newer players.

Beelining - Focusing on obtaining a technology early by only researching technologies needed to research it and no others. For example, to beeline Bronze Working, you'd research Mining and Bronze Working and nothing else until Bronze Working was finished.
Finisher - The bonus for completing a Social Policy tree (e.g. Free Great Person for Liberty.)
GWAM - Great Writers, Artists and Musicians. These are the three types of Great People who can make Great Works, a major source of tourism for cultural Civs.
Meatshield - Soaking up damage on behalf of something else. This can be on the small scale (like a Swordsman taking damage for an Archer) or on a large scale (protecting a capital city with less important cities.) This guide generally uses "meatshield" to refer to the small-scale version.
Opener - The bonus for unlocking a Social Policy tree (e.g. +1 culture for every city for Liberty's opener)
Tall Empire - A low number of cities with a high population each
UA - Unique Ability - The unique thing a Civilization has which doesn't need to be built.
UU - Unique Unit - A replacement for a normal unit that can only be built by one Civilization or provided by Militaristic City-States when allied (this only applies to land UUs that are of Civs not in your current game.)
Uniques - Collective name for Unique Abilities, Units, Buildings, Improvements and Great People
Wide Empire - A high number of cities with a low population each. Byzantium's cultural route works very well with this set-up.
At a glance (Part 1/2)
Start Bias

The Byzantine empire has a coastal start bias. This is to allow you to build Dromons as soon as possible. Religious and naval technologies are close together on the tech tree, which helps, too.

Uniques

Byzantium's UA is notably flexible - you can use it differently each game based on your starting position. Aside from that, they've got two UUs, similar to Carthage - one, an ancient naval unit and the other a classical mounted unit.

Unique Ability: Patriarchate of Constantinople

  • When founding a religion, you may pick a bonus belief in addition to the founder and first follower belief.
    • This belief may be any remaining belief except Reformation beliefs. Other Civs will benefit from a Pantheon or Follower belief if your religion is dominant in your city.
    • Choosing a Pantheon belief as your bonus does not count as a Pantheon belief for purposes of the Religious Tolerance tenet (so, if Desert Folklore is your Pantheon and Messenger of the Gods your bonus belief, rival cities which have the Religious Tolerance tenet and your religion as the second-biggest will only benefit from Desert Folklore.)
  • When founding a religion, you gain an extra 20 points compared to other Civs

Unique Unit 1: Dromon (Replaces the Trireme)


A naval ranged unit

Technology
Obsoletion
Upgrades from
Upgrades to
Production cost
Purchase cost
Resource needed

Sailing
Ancient era
2nd column
(3rd column overall)

Astronomy
Renaissance era
1st column
(8th column overall)

Galley
(40Gold)**

Galleass
(95Gold)*
56Production*
260Gold*
None
*Assumes a normal speed game.
**You can only acquire Gallies by capturing one while using the Prize Ships promotion. The upgrade cost shown assumes a normal speed game.

Strength
Ranged Strength
Moves
Range
Sight
Negative Attributes
Positive Attributes
8Strength
10Ranged Strength
4Movement Points
2
2
  • May not melee attack
  • Cannot enter ocean tiles
  • 50% bonus vs naval units

Negative changes

  • Costs 56 production in normal speed games, up from 45 (+24%)
  • Costs 260 gold in normal speed games, up from 220 (+18%)
  • Costs 40 gold to upgrade to in normal speed games, up from 20 (+100%)
  • No melee attack
  • 8 strength, down from 10 (-20%)

Positive one-off changes

  • Ranged attack (10 ranged strength, 2 range)
  • 50% bonus vs naval units
  • Upgrade cost of 95, down from 160 in normal speed games (-41%)

Miscellanious changes

  • Upgrades to Galleass rather than Caravel
  • Classified as a naval ranged unit rather than naval melee, hence uses naval ranged promotions

Unique Unit 2: Cataphract (Replaces the Horseman)


A mounted melee unit

Technology
Obsoletion
Upgrades from
Upgrades to
Production cost
Purchase cost
Resource needed

Horseback Riding
Classical era
1st column
(4th column overall)

Chivalry
Medieval era
2nd column
(7th column overall)
None

Knight
(100Gold)*
75Production*
390Gold*

1 Horse
*Assumes a normal speed game.

Strength
Ranged Strength
Moves
Range
Sight
Negative Attributes
Positive Attributes
15Strength
N/A
3Movement Points
N/A
2
  • 25% penalty vs cities
  • Can move after attacking

Negative changes

  • 3 moves, down from 4 (-25%)

Positive one-off changes
  • 15 strength, up from 12 (+25%)
  • Can receive defensive bonuses
  • -25% penalty vs cities, down from -33% (roughly 14% stronger vs cities assuming no other combat modifiers)
At a glance (Part 2/2)
Victory Routes

Note these scores are a matter of personal opinion based on experiences with the Civilization. You may discover a way of utilising the Civ more effectively in unconventional ways.

Cultural: 8/10
Diplomatic: 7/10
Domination: 8/10
Scientific: 6/10

The way Byzantium works, you should let the first few turns determine the best victory route. Vulnerable neighbours? Domination can serve you well. Strong neighbours? Use your UUs to defend during wide expansion and push for a cultural win. The details will be explained later in the guide.

It's also worth mentioning that Byzantium's heavily religious approach and pushing the limits of happiness can give them high scores relative to their actual power. While you shouldn't actively seek a score victory, (it's a backup if all else fails,) they have a mild head start on it compared to many other Civs.

Similar Civs and uniques

Overall

Byzantium's unique unit pairing is very similar to that of Carthage. Both have a slow-but-strong Horseman replacement and a Trireme replacement better in combat than the generic unit. Both also do well building wide, but for different reasons - Byzantium to emphasise faith output, and Carthage to maximise gold output.

Same start bias

The coastal start bias is the most common in the game. Aside from Byzantium, it's also the start bias of Carthage, Denmark, England, Indonesia, Japan, Korea, the Ottomans, Polynesia, Portugal, Spain and Venice.

Similar to the UA

Getting an extra belief is unique among Civs. Having an advantage to religion without a direct advantage to faith is shared only with Arabia, which can spread their religion more effectively along their trade routes than other Civs. Although Arabia and Byzantium's bonuses seem very different, the Religious Texts/Itinerant Preachers combination of beliefs for Byzantium acts similarly to Arabia's UA (helping out with religious spread without needing to spend faith) and is a very good all-round pick.

Similar to Dromons

The only other Trireme UU is Carthage's Quinqueremes, although that's a stronger melee unit rather than being a ranged unit with a bonus against other naval units.

Dromons are dominant in their era; they'll have the upper hand over any rival naval units until Galleasses come onto the scene. Similar dominant ranged naval units include Venice's Great Galleass prior to Astronomy, and England's Ship of the Line prior to Steam Power.

Similar to Cataphracts

Being also a slow-but-strong Horseman replacement, Carthage's African Forest Elephant is the unit most alike Cataphracts. They're a tiny bit weaker in combat and lack defensive bonuses, but they don't need horses to be built, generate Great Generals faster and make adjacent enemy units more vulnerable to attack.

Another Horseman UU is Greece's Companion Cavalry. It's also stronger than the generic Horseman, but has a speed bonus instead of a penalty, no defensive bonuses and an advantage at Great General generation.
Unique Ability: Patriarchate of Constantinople


Byzantium is unusual as Civs go. It's one of the few to have a UA that doesn't take effect immediately, but unlike Civs like the Iroquois or the Mayans, this offers an opportunity rather than a weakness. The ability to choose a bonus belief in your religion - from any type except reformation - is very flexible, and coupled with the fact it takes time to found a religion gives you the opportunity to choose the route that best-suits your starting situation.

Generally, the best options for the Eastern Roman Empire are to go cultural or go for domination. Consider the following factors:

Favours cultural victory

  • Lack of horses
  • Bad access to open seas
  • Nearby Civs with early UUs (makes invasion harder)
  • Desert start or a desert very close to the capital
  • Lots of resources near the capital which can provide lots of faith with the right Pantheon
  • Lots of land for new cities
  • Lack of Civs emphasising religion (Celts, Egypt, Ethiopia, Indonesia, Mayans, Siam, Songhai and Spain are the main rivals there)

Favours domination victory

  • Poor faith production
  • Lots of religion-emphasising Civs
  • Lack of decent city spots
  • 2 or more religious buildings taken (Cathedrals, Monastries, Mosques, Pagodas) before you can found a religion of your own
  • Plenty of horses and/or iron
  • Good open seas access and coastal rival Civs
  • Weak neighbours

A hybrid approach works too, by taking 2-3 religious building beliefs along with Sacred Sites to gain tourism and influence with other Civs making conquests easier, (the more cultural influence you have with a Civ, the less resistance there is for capturing their cities,) though that makes it slower to launch wars with your UUs.

A good time to decide is when you found your religion, as you can then choose the beliefs that best-support your gameplay style. But there's one problem - Byzantium has no bonuses to faith generation, hence founding the religion in the first place harder than for any other religion-emphasis Civs. The best way to make sure you aren't shut out of your UA is to take Piety as your first Social Policy tree, taking advantage of fast Shrine and Temple building as well as the extra faith from both.


Above: Having a desert start, I chose the cultural route. But all the faith generation in the world doesn't help with religious wonders - I lost this one being only one turn away.

So, to summarise these first points, get a religion as soon as you can and use your starting position to determine your victory route, and choose beliefs as appropriate.
Religion: Pantheons
Usually, I'd put this section later on after the bit on Social Policies and Ideology, but the nature of Byzantium's game is that strategies rest on your religion, and hence it's a good idea to explain the options before going further. Let's start with Pantheons. They're pretty much the same whether you're warmongering or going for culture.

It's important to ensure you actually get a religion rather than making your UA useless, and a faith-boosting Pantheon is usually your best option. Here's your best choices.

Desert Folklore

The strongest pantheon for faith generation, but if you can't reach desert early on, choose a different pantheon.

Dance of the Aurora

A weaker version of Desert Folklore if you start near tundra.

Earth Mother, Goddess of Festivals, One with Nature, Religious Idols, Stone Circles or Tears of the Gods

These six are weaker, situational options for faith generation. If you can't manage Desert Folklore or Dance of the Aurora, you may have the right resources for one of these options.

Earth Mother is decent if you start near copper, iron and/or salt, Goddess of Festivals for wine and/or incense, One with Nature for a natural wonder, Religious Idols for gold and/or silver, Stone Circles for stone and/or marble and Tears of the Gods for gems and/or pearls.

Messenger of the Gods

An option if you've either got good faith generation thus making pantheon faith redundant, or you fail to get a decent faith pantheon. It offers every city with your religion +2 science, which seeing as you'll likely have a large number of cities later in the game (either through wide expansion or conquest) is a good choice to offset the increased technology cost.
Religion: Cultural Route
If you've decided to go down the cultural route, you'll have a somewhat unusual path to victory. Byzantium's cultural route depends on the Sacred Sites reformation belief to get as much tourism as possible early on. The belief offers 2 tourism for every faith-purchased religious building (Cathedrals, Mosques, Monastries and Pagodas.) Byzantium's particularly good at going down this route as you can grab two religious building beliefs as soon as you found a religion, and possibly take a third one upon enhancing it.

This early-tourism route can also be decent for warmongers, as it offers you happiness through religious buildings (supporting occupied/freshly conquered city unhappiness) along with influence in other Civs due to the tourism advantage (cutting the time conquered cities rebel for.) The following section will cover alternative warmongering religious setups.

Founder

Church Property or Tithe

Having lots of cities costs a lot in building maintenance, and while the cities are growing, they're not going to contribute a lot of gold themselves. As such, here's an option for you.

Ceremonial Burial or Peace Loving

The happiness contribution's low at first, but one possibility is to use your bonus belief for an enhancer instead of a religious building, and take both Religious Texts and Itinerant Preachers to make your religion dominant and thus get quite a bit of happiness. This'll come at the cost of a potential faith building, though, so you'll need to expand a lot to make up for it.

Interfaith Dialogue

Wide empires have weak science. Being able to pour excess faith into Missionaries in order to get a little boost is rather handy.

Pilgrimage

For the event that your faith generation's fairly weak. Be sure to spread your religion fairly quickly before rival religions use a faith advantage to convert lots of cities, thus making it harder for you to convert cities yourself and get the faith to defend against Missionary spam.

Follower and Bonus

Your follower and bonus beliefs should consist of as many faith buildings as possible. You'll get the best tourism output if you take three (or have the means of spreading a rival religion with faith buildings to your lands.) If you can't get two religious buildings, then you may be better off going down the warmongering route.

Pagodas

The strong happiness contribution these bring makes building wide (and hence getting space for even more religious buildings) easier. Because this is belief is highly-desired by a range of Civs, take it as soon as you can.

Mosques

High faith contribution lets you build a steady number of religious buildings or churn out Missionaries to keep your religion strong.

Cathedrals

Great Art slots are quite rare prior to the industrial era, so having more will help ensure you can fill all those Great Work slots.

Monasteries

Higher priority if you have plenty of wine and/or incense, otherwise this is the lowest priority out of the four faith-bought buildings, seeing as it doesn't provide happiness.

Backup Follower

If you fail to get a religious building when enhancing your religion, here's a few choices for that second follower belief.

Religious Centre or Asceticism

Seeing as you should be taking the Piety Social Policy tree, Shrines and Temples are very cheap to build. Hence, it's a really easy source of happiness if you need a little quickly.

Divine Inspiration or Liturgical Drama

If your faith generation is fairly poor at this point but you have a wonder or two, Divine Inspiration is an effective way of getting it going. Alternatively, Liturgical Drama offers faith for Ampitheatres. The latter takes a little longer to get going, but will offer you more faith in the long-run.

Alternative Bonus

Taking a non-religious building for a bonus belief when you're going down a cultural route is risky, but it can pay off with a very strong religion.

Religious Texts or Itinerant Preachers, to complement the other

This'll make your religion the best at pressure. Itinerant Preachers makes your religious pressure stronger by cities from further away backing each other up, while Religious Texts helps out with pressure anyways. It's a decent combination if your faith production's low, as it frees up some faith you would be using for Missionaries, and can make your founder belief stronger (if it's one based on followers or cities.)

Church Property or Tithe, to complement the other

A lovely combo for getting cash. For one thing, it means you can hold off getting money buildings and suchlike, giving you more time to build units or whatever else you like.

Enhancer

Religious Texts or Itinerant Preachers

See the Alternative Bonus section, but this time you're only taking one of them. Takes some pressure off using faith for Missionaries.

Reliquary

If your faith production's struggling a little, this is the only enhancer belief that offers it.

Reformation

Sacred Sites

If you want to win culturally as Byzantium, it helps to get this going as soon as possible. A little bit of tourism early on can be quite significant later in the game.


Above: It's the 11th century. Considering I only got two religious building beliefs, rather than three, and that I have relatively few cities, that amount of influence ain't bad. Note the science bonus for trading with Civs I influence - that helps offset the higher technology costs from having more cities to maximise tourism output.

To get the most tourism, you need strong faith generation to build those faith-purchased religious buildings, and plenty of happiness to support all those cities. Luckily, faith-purchased religious buildings can provide both, though you'll probably need to build Colosseums and suchlike as well to support the need for happiness. That still needs faith in the first place, but the Piety tree's halved time to build Shrines and Temples along with +1 faith to each makes getting your faith generation off the ground somewhat easier.


Above: The Piety Social Policy tree's Mandate of Heaven makes religious buildings cheaper to faith-purchase, making it cheaper to get tourism going.

To the Glory of God

A backup if you can't manage Sacred Sites. It lets you get any non-unique Great Person through faith, which is particularly good for rushing wonders with Great Engineers or getting Great Scientists to help cover any disadvantage in science you may have.
Religion: Alternative Warmongering Beliefs
Maximising early tourism generation makes capturing cities earlier, but if you're single-mindedly focusing on war, there's stronger religious combinations at the cost of less flexibility. Generally, you should use your bonus belief either for a Founder or Enhancer belief (they tend to be more powerful than others,) though the specific choice is fairly open depending on your game or personal preferences.

Founder

Church Property and/or Tithe

Maintenance costs are a major challenge to overcome in early wars, making a cash-granting belief rather handy.

Pilgrimage

Prioritising faith-granting beliefs and taking Holy Warriors is a decent way to combine your UA and Cataphract UU (you can't faith-purchase naval units, so you can't do the same to Dromons.) Pilgrimage requires you to spread your religion to foreign cities, so you may as well take the Just War Enhancer belief with it to help out wars further.

Follower

Holy Warriors

A risky choice seeing as it relies on getting your faith generation going early on. Still, if you can make enough faith, this could squeeze in an extra Cataphract or Catapult or two.

Asceticism

Mostly a complement to Holy Warriors as a source of happiness without using faith. Piety's opener makes building Shrines practical in even the smallest cities.

Pagodas

If you don't want to risk Holy Warriors (or you want to maximise faith output ahead of using Religious Fervour) then faith-purchased buildings are a good option. As is nearly always the case, Pagodas are the best due to their 2 points of happiness.

Mosques

More faith and less happiness than Pagodas. Again, good for maximising faith output before getting Religious Fervour.

Enhancer

Just War

It's unlikely you'll be converting rival cities before you launch any Cataphract-led raids (if you do decide to go to war at that point,) but this belief is still powerful for combining religion and warmongering.

Religious Texts and/or Itinerant Preachers

Taking one of these with Just War is a good way to ensure enemies can't as easily convert their cities away from your religion while you're fighting them. Alternatively, taking both makes the spread of your religion particularly difficult for rivals to stop, making your Founder belief more potent.

Reformation

Religious Fervour

By focusing on faith generation and religious strength, you can get quite a few units out the door later in the game with this belief. Remember that like Holy Warriors it only works for land-based military units, not civilians, navies or air forces.

Unity of the Prophets

If you're taking Just War and/or Pilgrimage meaning you've got a large incentive to convert foreign cities, Unity of the Prophets makes it harder for those Civs to undo that. It's particularly handy for dealing with Civs with a faith-generation advantage.
Unique Unit I: Dromon



Byzantium's unique unit situation is similar to Carthage - a Trireme replacement and a slow but strong Horseman replacement. Dromons differ from Quinqueremes by being slightly more expensive, a bit weaker but possessing a ranged attack and having a huge bonus against other naval units.

Dromons are best at cleaning up units without taking much damage itself. It's the only ranged naval unit until the late medieval-era Galleass, meaning you can use the range to pick off Gallies and Triremes with little trouble - with a 50% bonus versus other sea units, you can usually take them out in two hits. Due to the Dromon's strength and the relative rarity of Galleasses, (due to their positioning on the tech tree,) it can remain dominant in the seas until the Renaissance era.


Above: Alright, I do have a large bonus against Barbarians making the odds very favourable. But the 50% bonus against sea units helps; if I took Targeting promotions I could probably take the Galley down in one hit.

Whether you're aiming to win by war, culture, or something else entirely, Dromons are well worth building due to their unrivalled ability to repel Barbarian fleets at this stage of the game, thus making excellent defenders of coastal trading routes. While they're slightly more expensive than normal Triremes, having a ranged attack means you don't need to send them back to your lands to heal up as much thus making them significantly more cost-effective.

But that's not all. Being a ranged sea unit rather than a melee one, Dromons use the ranged naval promotions. That includes the Bombardment line - each of the three promotions increasing the Dromon's strength against land units by a third. Backed by a Barracks, you have a unit which costs the same as a Spearman but has a ranged attack, moves faster and can deal almost as much damage against land units as a Horseman can.

Aside from unit-killing, Dromons can also be used reasonably well to attack cities with. Although they can't capture them directly (you can use a Dromon to escort an embarked melee unit to get the final hit on a city), they're still good at destroying their defences. Dromons have the same speed, cost and damage output as Chariot Archers without the need for horse resources - albeit with worse defence against the ranged attacks of cities (ranged naval units use their melee strength when defending against ranged attacks, while ranged land units use their ranged strength, so Dromons will defend with a strength of 8 rather than the 10 Chariot Archers defend with.)

Special promotions kept on upgrade

None - the 50% bonus against naval units may look like a promotion, but it isn't kept.

Note that the Dromon upgrades to the Galleass, but doesn't go obselete until Astronomy. Because of the bonus versus naval units making Dromons almost as powerful as Galleasses (in attack, at least) coupled with the fact Galleasses are almost 80% more expensive than Dromons, it might be worth continuing to use Dromons at that brief point.
Unique Unit II: Cataphract



Before we get on to the good stuff, there's a couple of issues with Cataphracts to understand. First and foremost, they still require horses unlike Carthage's African Forest Elephants (the other slow-but-strong Horseman UU.) Researching Animal Husbandry very early on in order to locate them isn't a bad idea. The second point is their position on the tech tree - it's in a different direction to religious and naval technologies, so unless you're seeking to take Cataphracts to invade enemy lands, don't expect to have lots early.

In defence...

For a cultural Byzantium player, or a warmonger who seeks not to rush things, Cataphracts serve as a decent defensive unit. They've got more strength than every Classical-era or earlier unit bar one (the Roman Legion) and unlike other mounted units benefit from defensive bonuses allowing them to fortify or use terrain advantages. Higher strength combined with fortification bonuses can even give you balanced odds against Spearmen - normally the Cataphract's counter.

With the Dromon in the seas, and Cataphracts on land, you have a rather efficent defensive force in the early-game, which allows you to more comfortably expand without stretching too thin. That's helpful for taking full advantage of the Sacred Sites Reformation belief.

In attack...

Cataphracts can be thought of as mobile Swordsmen. They're decent at fighting other units, but you'll need to bring Catapults to bring down cities. Still, even then, with a slightly reduced penalty against cities, Cataphracts can help a little at that job, too (though they're only a quarter of a strength point stronger than a Spearman at fighting cities.)

Of course, Cataphracts suffer from less mobility than regular Horsemen, but three moves and the ability to move after attacking still means you can use a unit adjacent to a city to attack and then retreat two tiles, out of range of any retaliation. Plus, Catapults only have two moves slowing down the army anyway.

Compared to Swordsmen...

Let's expand on the point of likening Cataphracts to mobile Swordsmen by comparing the two. First, let's get the negatives out the way.

  • Vulnerable to Spearmen
  • Slightly higher tech cost (assuming a beeline)
  • 25% penalty vs cities

And here's the advantages:

  • 15 strength, up from 14 (+7%)
  • 3 moves, up from 2 (+50%)
  • Can move after attacking
  • Requires horses rather than iron (an advantage as horses are uncovered earlier making them easier to acquire early)
  • More useful technology route (assuming a beeline)

So, while Cataphracts may not be able to attack cities as well as Swordsmen, they're good at blocking enemy units (with extra mobility) and mildly better at defending. And as such, they make better meatshields; the main point of Swordsmen.

To conclude...

Cataphracts are a kind of land-based version of the Dromon in the sense that they make decent defenders and are better at fighting units than cities. Unlike Dromons, Cataphracts can soak up attacks from cities reasonably well which makes them good escorts for Catapults. Their main asset is efficency - they lack same-era counters, meaning you don't need a complicated array of other units to back them up in war.

Special promotions kept on upgrade

None.
Social Policies: Early-game choices
Byzantium's one of the few Civs that can start in the Piety tree (if you're really struggling to get enough faith early on). If you're playing culturally, complete the whole thing. If you want to take your UUs to war, then you can switch to Honour for a few policies after Organised Religion and complete the Piety tree later.

Otherwise, a safer option will be a hybrid of Liberty and Piety. Building wide will help out your faith output, and Piety will contribute on top of that.

Afterwards, if you're playing culturally, Aesthetics and Exploration will back you up nicely. Alternatively, take Rationalism after Liberty/Honour and Piety to help keep your tech rate up.

Liberty

Opener

Liberty's Opener offers something Piety's does not - culture. This helps with getting the next few Social Policies sooner, and also means your cities automatically expand their borders without needing Monuments built.

Republic

A production bonus in all your cities will aid in setting up sooner - including religious buildings.

Collective Rule

With cheaper Settlers and a free one, it's quite a bit easier to expand to lots of new cities which you can build up with faith bonuses. Be sure to use the "Avoid Growth" option on the city screen if your many cities start straining your happiness.

At this point, it's generally a good idea to switch to Piety, so you can get to Reformation and still have time to switch to another tree before ideologies.

Piety

Opener

Halving the time to build Shrines helps out greatly with early-game faith generation. Shrines with the Piety opener are cheaper than Monuments (at this stage of the game, at least) meaning pretty much any city can build them without spending very long.

Organised Religion

Get more out of the religious buildings you already have. This policy will probably take off quite a number of turns on the way to founding a religion, hence is well worth picking up. If you want to go for an early war, consider switching to Honour now to pick up a few policies there.

Religious Tolerance

Well, whether or not a rival religion is established enough yet for you to take advantage of this policy, you're going to need it for Reformation. Later in the game, when rival religions come, choose one with a good Pantheon and focus your Missionaries/Inquisitors/Great Prophets on keeping down the rest (assuming you have the excess faith to do so.)

Reformation

Most Reformation beliefs are focused on the Industrial-era and later (hence a warmongering Byzantium can hold this policy off for quite some time if they're fairly sure no-one will grab the belief they want.) Sacred Sites for the cultural route, however, is quite the opposite - the sooner you have it, the better.

Mandate of Heaven

This saves a considerable amount of faith which makes filling new cities full of faith-purchased buildings easier.

Theocracy

If the base gold of a city is 8 or more, Temples become essentially free to maintain, and if the base gold is over 12, your two religious buildings raise you more cash than they cost you. Holy Sites also get a decent amount of cash with this. However, it takes time for this policy to reach its full effect (and Theocracy's a dead-end policy) hence meaning it's fine to leave it until last.

Finisher

If you haven't enhanced your religion yet, now's your chance. Chances are though, you have. If you're playing culturally, building a Holy Site is a decent idea. Not for the culture, but for the good faith generation at a stage where you may need it. Warmongers will probably gain more out of pushing their religion into rival lands, taking advantage of Just War and suchlike.

Honour (Warmongering Byzantium favoured)

Opener

Tracking down Barbarian encampments prevents your army being ambushed by them on the way to enemies, and being able to farm culture off them compensates for the lack of culture offered by Piety's opener (Piety being the only Ancient-era tree lacking a cultural bonus in its opener.) It's a good idea to send some Cataphracts off killing Barbarians up to the experience cap (30XP) while the rest of your army's being built.

Discipline

The 15% bonus applies to all non-ranged military units (including sea units, but Dromons don't gain here) letting your Cataphracts fight even more effectively than is already the case. Taking this policy first after the Honour opener is to ensure it's actually in effect when you launch your attack (taking it later could be too late.)

Warrior Code

If your culture generation (or ability to kill Barbarians quickly) is strong enough, then hopefully you can take the free Great General before your war gets going, giving you a 15% strength advantage over Civs not taking Honour (on top of Discipline.) Otherwise, faster melee unit production will still be useful for medieval warfare.

Military Tradition

Around this point, switching back to Piety and finishing it off to strengthen your religion may work well, though it can also be worthwhile to finish Honour for the long-term military bonuses. It's your choice depending on the situation you're in. Military Tradition's 50% bonus to XP gain is only really useful when you're at war, so hold the policy off if the early war's over.

Military Caste

If you're going for a hybrid cultural/warmongering approach, taking the cultural religion but using your uniques for some early warmongering, this policy really shines for helping you build lots and lots of cities without as harshly hurting happiness and culture. Even if you're just focusing on pure warmongering, an easy source of culture and happiness is still good.

Professional Army

Like most Civs with early UUs, you'll probably have a lot of unit upgrading to do, and cutting the costs of that can save a considerable amount of gold in the long-run. Cheaper XP buildings make it easier for lower-production cities to contribute towards a good army later on in the game.

Finisher

Getting gold as you kill units is useful as a source of quick gold when needed (for example, to upgrade a unit.) A good way to get plenty of kills when out of war is to bring a Dromon/Frigate around the coast searching for encampments, then just kill any Barbarian that spawns in them. Plant units around the encampment so other Civs can't take them out if you have to.
Social Policies: Mid-game choices
Aesthetics (Cultural Byzantium favoured)

Opener

While it is possible to get a very early cultural victory with Sacred Sites alone, typically you'll need more conventional tourism generation as well. Right away, you get a 25% bonus to GWAM generation, meaning you can produce more Great Works. Just ensure you have all the slots - Great Art in particular is difficult to fill before the industrial era unless you have the Cathedrals belief.

Cultural Centres

Faster Monument building gives you a better shot at getting the National Epic up, which should go in a GWAM-generating city for maximum impact. As for the other buildings you can more cheaply build, they all have Great Work slots of varying kind. That's very useful for building Ampitheatres in low-production cities, ensuring you can fill those Great Writing slots in particular.

Fine Arts

Byzantium won't have much in the way of excess happiness when playing culturally, as Sacred Sites becomes stronger the more cities you have. You need this policy to get further in the Aesthetics tree, but aside from that, you won't see much use out of it.

Flourishing of the Arts

Again, this policy is more designed for tall-building cultural players, as it's harder to get wonders when you're building wide. To maximise this policy's effect, you can use Great Engineers to rush wonders in cities that don't have any already, but then again, those cities are likely not to have a particularly high cultural output. So, again, this policy is mostly for the sake of later policies.

Cultural Exchange

Now we're talking. Owning lots of religious buildings is a good incentive for other Civs to take your religion, which now gives you an even bigger bonus to tourism. You're also getting more tourism out of Trade Routes (hence it's a good idea to send them to a large variety of Civs) and open borders. It doesn't affect Diplomat propaganda bonuses.

The real potential of this policy for Byzantium comes in the point that most Civs won't have got their tourism generation really going yet, but Byzantium has. Shared religions, Trade Routes and open borders can all be utilised in the medieval era, and together with this policy they can more than double your tourism output - making an early cultural victory closer to reality.

Artistic Genius

Essentially a free piece of Great Art. Not the strongest policy around, hence it's fine to take it last.

Finisher

Aesthetics' finisher is a kind of insurance if you can't get a strong tourism lead. If you've got 2-3 religious buildings, by the industrial era you'll have a high faith generation for buying GWAMs with, helping to further bump up your tourism. You can build lots of Museums and Archaeologists in the late-game to take advantage of doubled theming bonuses.

Exploration (Cultural Byzantium favoured)

Opener

This tree's somewhat of a mixed bag, but a coastal starting bias combined with a cultural focus encourages you to go into Exploration. For example, your ex-Dromon navy can better-defend you by moving faster and seeing further with this opener and it's needed for the Louvre wonder - one of the better cultural wonders around.

Maritime Infrastructure

Coastal cities often struggle for production, and this policy helps address that issue. Simple, really.

Naval Tradition

An easy source of happiness. At this stage, you may lack the room for building more cities, so happiness can be focused on building cities taller (so they can build more cultural buildings, wonders or that kind of thing.)

Merchant Navy

Naval Tradition's happiness is now cheap to maintain, too.

Treasure Fleets

Having more gold avaliable is a good way to push the World Congress the way you want, or bribe Civs into letting you have open borders for the tourism bonus.

Navigation School

The main point of the policy is getting the finisher. Of course, a free Great Admiral can help you fend off attacks from the seas, but generally this policy's more of a stepping stone for you than anything else.

Finisher

Building wide gives you plenty of Antiquity Sites within your land - now there's even more. Make sure you have plenty of Museums to store them in.

Rationalism

Opener

Rationalism's somewhat of a one-size-fits-all Social Policy tree, which makes it a good choice no matter your victory route. Better science keeps your tech rate up and hence helps to prevent your military might falling behind. The opener right away gives you +10% to science so long as your empire's happiness level is positive.

Humanism

If you're off warmongering and don't really need GWAMs, you may as well generate Great Scientists instead. Prior to around the Plastics tech, plant Academies with them and later on, use them to rush technologies.

Free Thought

Like the opener, but even stronger. You already may have a number of trading posts to fund armies, so getting science out of them too is highly useful. And the bonus from Universities is probably better in itself than what the opener offers.

Secularism

Humanism encourages you to generate Great Scientists, which typically means having plenty of Scientist specialists. Now, you can squeeze even more science out of them. This policy probably isn't anywhere near as strong as Free Thought for Byzantium, but science is good for pretty much everything.

Sovereignty

Takes some of the cash out of science building maintenance and back into military maintenance or suchlike.

Scientific Revolution

If you have a fair bit of free cash floating around (maybe you took Tithe and are spreading your religion far and wide) then you can convert that into science - so long as other players don't get concerned at any military ambitions you might have.

Finisher

You can pour excess faith into handy Great Scientists, as well as that free technology. Consider timing the policy in order to get a tech that's expensive.
Ideology
Building wide lends itself to the Order ideology if you're going for culture. Freedom also works (Media Culture and the CN tower together guarentees you +33% tourism in every city) but the level 1 and 2 tenets are less effective for wide empires. If you're warmongering, Autocracy is a little more war-focused. Autocracy's also the best for a war + culture hybrid.

As ever, I'll go through the best options for the first "inverted pyramid" of tenets, so that's three from level one tenets, two from level two and one from level three.

Level One Tenets - Order (Cultural Byzantium)

Socialist Realism

With Cultural Centres in the Aesthetics tree, this lets you put up Monuments at breakneck speeds. More importantly, it now offers as much happiness as a Colosseum which is useful as you need the happiness in order to take advantage of Dictatorship of the Proletariat - the level three Order cultural tenet.

Hero of the People

Generate Great People faster, therefore generating GWAMs faster, therefore more Great Works, therefore more tourism, therefore win the game slightly faster. Hopefully.

Young Pioneers

Again, the idea is to support the Dictatorship of the Proletariat.

Level Two Tenets - Order (Cultural Byzantium)

Note: Use Cultural Revolution as your first option if the main cultural Civs to overcome are taking Order.

Workers' Faculties

While cultural players can afford to fall behind slightly in technology, you can't make a habit of it. 25% extra science is no small amount, and with faster Factory building, you can let the scientific and production advantages spread throughout your lands.

Academy of Sciences

Yep - that's right, even more happiness. The level of happiness rivals have can be tricky to overcome (though ideological pressure helps.) And building very wide doesn't help with your own happiness, so you need practically every little bit you can get.

Level Three Tenet - Order (Cultural Byzantium)

Dictatorship of the Proletariat

Now, try to get as much happiness (and tourism, obviously) as possible. Send your Great Musicians to Civs with plenty (India usually dominates in that respect) and use your early Sacred Sites - assisted cultural advantages to win.

Level One Tenets - Autocracy (Warmongering Byzantium)

Industrial Espionage

Gotta keep that tech rate up. If you took Sacred Sites in your religion, the tourism advantages combined with this makes for extra-fast tech stealing.

Mobilisation

A gold-focused religion (e.g. Tithe and/or Church Property) provides plenty of cash for buying units with by the late-game. This tenet makes that even cheaper.

Elite Forces

An all-round useful bonus for any warmonger (except Japan.) The description of dealing 25% more damage is misleading, however - the tenet merely closes the gap between wounded units and ones at full health by 25%. Still useful though, giving you an edge over opponents without it.

Level Two Tenets - Autocracy (Warmongering Byzantium)

Lightning Warfare

Whatever happened to Cataphracts? They became Tanks, that's what. Ironically, this policy gives those units the exact opposite utility Cataphracts had - fast, attacking units rather than relatively slow meatshields. Still, this policy gives a good reason to hang on to those old former-Cataphracts.

Nationalism

Goes well with Mobilisation to help churn out more units.

Level Three Tenet - Autocracy (Warmongering Byzantium)

Note: Hybrid cultural/domination players should take Cult of Personality. They can take both that and Clauswitz's Legacy for a powerful cultural warmongering combination.

Clauswitz's Legacy

While temporary in nature, if you're fast with this policy, you can put yourself in a winning position by the time the 50 turns wears off. With Lightning Warfare, Tanks are brutal in attack, though don't forget about planes, sea units and suchlike too.
World Congress
Here's a list of the decisions and brief notes on importance of some. Ones missing depend greatly on the situation you're in, though you should try to push your own religion as the World Religion if possible. Voting choices may vary depending on your game.

Here's a list of the decisions and brief notes on importance of some. Ones missing depend greatly on the situation you're in. Voting choices may vary depending on your game - if everyone's pushing for a policy you don't want, but your strategy doesn't rest on it, then it may be better just to abstain (or vote for it for possible diplomatic bonuses.)

Note "priority" refers to how high you should prioritise your votes if it comes up, not how much you should prioritise putting them forward.

Arts Funding

Low-Medium priority if you're warmongering
High priority if you're cultural
Vote no if you're warmongering
Vote yes if you're cultural

Cultural Heritage Sites

Low priority if you're warmongering
Medium-High priority if you're cultural
Vote no if you're warmongering
Vote yes if you're cultural, unless a single rival has a lot of wonders

Building wide, it's hard to get hold of wonders. Even if you're playing culturally, therefore, think carefully before you end up voting for this policy - you could help out a Civ like Egypt or India more than you help yourself.

Embargo City-States

Medium priority
Vote no if you're warmongering
Vote yes if you're cultural and have plenty of trading partners, thus having no need for City-States

Historical Landmarks

Low priority if you're warmongering
High priority if you're cultural
Vote no if you're warmongering
Vote yes if you're cultural

International Games

High priority
Vote no if you're warmongering
Vote yes if you're cultural

International Space Station

Medium-High priority
Vote no

Because Byzantium isn't particularly strong on science down the cultural and warmongering routes, you can't let that pass.

Natural Heritage Sites

Medium priority
Vote yes if you've got Natural Wonders of your own and a cultural rival doesn't have more than you

Nuclear Non-Proliferation

Medium priority
Vote yes if you have plenty of nuclear weapons (and rivals don't,) you lack uranium and other players have it, you're the only player with nuclear weapons or you're playing culturally. Vote no otherwise.

Scholars in Residence

Medium-High priority
Vote yes unless you're in the lead technologically speaking

Sciences Funding

Low priority
Vote yes if you're warmongering
Vote no if you're cultural

Standing Army Tax

High priority if you're warmongering
Low-Medium priority if you're cultural
Vote no if you're warmongering
Vote yes if you're cultural

World's Fair

Low priority if you're warmongering
High priority if you're cultural
Vote no if you're warmongering
Vote yes if you're cultural
Wonders
If you're going for early war, avoid early wonders (aside from possibly the Statue of Zeus.) Byzantium as a whole generally has a problem with building wonders due to the fact religious bonuses encourage you to build wide (wide empires have higher faith generation.) Still, here's a selection of the best wonders to take.

Ancient Era

Pyramids

Got a lot of cities that need developing quickly? Don't have culture to spare for Liberty's Citizenship? The Pyramids have you covered. Thankfully, they're not a very competitive wonder (the AI tend not to pick it up for quite some time into the game) so you can risk putting it off a little and waiting for your biggest city to develop before building it.

Statue of Zeus (Honour Only, hence Warmongering Byzantium favoured)

This brings the city attack penalty of Cataphracts down to 10%, which makes them almost as effective as unboosted Swordsmen against cities. (0.5 points below, or 2.6 below a Statue of Zeus-boosted Swordman.) Of course, it also makes other stuff better against cities, too, which makes the wonder greatly useful over the course of the game. Honour exclusivity makes the wonder uncompetitive, and it's fairly cheap to build.

Stonehenge

Helps to get your religion off the ground. If you've got a high-faith Pantheon like Desert Folklore, it may be more worthwhile to focus on infrastructure or a different wonder instead.

Classical Era

Colossus (Warmongering Byzantium favoured)

Maintenance costs are the bane of early wars. Luckily, the Colossus falls within the line of military technologies, and having a coastal startbias aids in building it.

Great Lighthouse

If you feel like making Dromons stronger, here's a nice option for you. If you're playing Culturally, it can still be good, but the Oracle and Parthenon are higher priority.

Oracle (Cultural Byzantium favoured)

Being on a similar technology path to many cultural things, the Oracle isn't the hardest wonder in the world to build and helps you in pushing your way to Reformation faster.

Parthenon (Cultural Byzantium favoured)

One of the earliest sources of tourism in the game, (if not the earliest,) the Parthenon helps complement Sacred Sites tourism. It's a risky wonder to build, though - you'll probably find it easier to pick up something else instead.

Medieval Era

Alhambra (Warmongering Byzantium favoured)

While it does make the city that built it generate 20% more culture, a cultural-leaning Byzantium has its hands full with other wonders and doesn't typically generate as much culture as other Civs going down the same path, hence getting less out of it. The main point is the free Drill I promotion, aiding in building new land non-ranged military units.

Borobudur

The first of the three Theology wonders. You're probably not going to get them all, so be careful with your priorities. I'd favour the Great Mosque of Djenne first. Despite Piety exclusivity, it's relatively competitive to complete and is the strongest wonder of the three. Borobudur comes second if you think you'll manage to finish the Great Mosque of Djenne, as you can stack the bonuses of the two wonders to provide 9 spread religion uses.

Great Mosque of Djenne (Piety Only)

Offering a Mosque without having to spend faith is one great benefit of this wonder, saving at least 160 faith on a normal speed game. Of course, the main advantage is that you get up to 50% more out of Missionaries, which saves faith you can use for religious buildings or buying units.

Hagia Sophia

If you're in need of more faith but your religious spread is reasonable, consider building this wonder and building a Holy Site with the free Great Prophet. In most scenarios, though, favour the Great Mosque of Djenne above this wonder.

Machu Picchu

Having lots of cities means having loads of population points by the end of the game, and Machu Picchu really helps out in that regard

Notre Dame

Whether building wide for culture, or heading into war, happiness is likely to be a problem in the midgame, which the Notre Dame is great at dealing with.

Renaissance Era

Globe Theatre

Great Literature slots become harder to fill as time goes on, due to Amphitheatres being the only normal building with them. Enter the Globe Theatre. Problem solved. Or at least delayed.

Leaning Tower of Pisa

A wonder in high demand so hence hard to build. While a cultural-leaning Byzantium will find this highly useful for GWAM generation, warmongerers still find use with other Great People. Plus, there's the free Great Person it grants.

Sistine Chapel (Cultural Byzantium favoured)

While Byzantium's approach to tourism doesn't lead to particularly strong culture generation, getting the wonder denies more cultural Civs it, helping you to overcome them with tourism.

Uffizi (Aesthetics Only, hence Cultural Byzantium favoured)

If you don't have the Cathedrals belief, Great Art slots can be hard to come by until the industrial era. So here's an option that helps solve that problem.

Industrial Era

Louvre (Exploration Only, hence Cultural Byzantium favoured)

Four slots to fill and a tourism bonus of 8 (with the Aesthetics finisher) up for grabs. A nice chunk of tourism there.

Modern Era

Broadway (Cultural Byzantium favoured)

A free Great Musician is a tourism bonus whether you make a Great Work or send it into foreign lands. Hence, this wonder's useful. Plus, there's the three Great Music slots and theming bonus to consider.

Eiffel Tower (Cultural Byzantium favoured)

Easy tourism! And a bit of happiness, which is vital for an Order-based culture strategy.

Prora (Autocracy Only, hence Warmongering Byzantium favoured)

Having masses of happiness isn't typical of warmongerers, so any boost to happiness is welcome.

Atomic Era

Great Firewall (Cultural Byzantium favoured)

The point here is to slow down the efforts of rival cultural Civs, and also deny the chance for cultural Civs to get it. Also, it can free up a defending Spy in the city to become a Diplomat for the propaganda tourism boost.

Pentagon (Warmongering Byzantium favoured)

With two early UUs, that's a lot of upgrading that needs to be done over the course of the game. Making that cheaper frees up more cash for buying new units.

Sydney Opera House (Cultural Byzantium favoured)

With a coastal start bias and a cultural leaning, this is a fairly good wonder to get. Importantly, it denies taller-building cultural players to get this wonder, which would make overcoming them with tourism harder.

Information Era

CN Tower (Cultural Byzantium favoured)

Byzantium's cultural strategy is about having lots of small cities. While Amphitheatres aren't hard to build for Great Writing slots, and Great Art slots become plentiful by the late-game, Great Music slots are trickier, as it takes a while to get to Opera Houses. The CN Tower's free Broadcast Towers for every city solves that problem.

Of course, by this stage of the game, you may just use Great Musicians for tourism against a specific Civ instead, in which case just enjoy the maintenance-free culture boost.
Pitfalls to Avoid
Byzantium's a fairly strange Civ, so making slip-ups is only normal. Here's a list of miscellanious pitfalls to avoid, which may or may not have been already covered earlier in the guide.

Only accounting for culture and domination victories

I've only covered those two victory types because they're the ones Byzantium's best at, but a strong gold-focused religion works towards a diplomatic victory, and Jesuit Education is a great way to push towards a scientific victory. If both domination and culture look unviable but you haven't founded your religion yet, consider one of those paths.

Going for lots of wonders early on

Byzantium does best building wide, and wide Civs aren't great at building wonders. Focus on the ones you feel are the highest-priority ones, not just all of them.

Not opening the Piety tree very early on

If you don't establish a religion as Byzantium, you lose your UA, which is the base of all your strategies. Unlike other religious Civs, you have no bonus to faith generation, so you need to complement faith gain with the Piety tree. Get the opener and Organized Religion out of it, at least.

One exception is duel maps seeing as the number of religions is equal to the number of players, but even then opening with the Piety tree is useful to get your UA going sooner.

Taking Religious Art

It's easy to assume that a belief with a bonus to tourism is a great idea, but for Religious Art to have any effect, you need the Hermitage, and for that you need an Opera House in every city. That's incredibly difficult if you're building wide to take advantage of Sacred Sites.
Dancer, Empress, Actress, Deceased: The Counter-Strategies
Byzantium defends well in the early-game, and its religion can dominate the world, but it has some significant vulnerabilities.

Playing against the Patriarchate of Constantinople

Byzantium may get themselves a nice religion, but they have to get there first, and with no bonuses to faith generation, many Civs can exploit that vulnerability. Other religious Civs can establish a religion first, thus shutting Byzantium out of certain beliefs. And if enough Civs found a religion fast enough, Byzantium can be completely shut out of their UA - one of the only times this is possible.

That's a bit of an extreme example, but one thing practically any Civ can do to damage a culturally-leaning is to take one of the religious buildings as a follower belief when founding a religion, so when Byzantium enhances their religion, they've got one less option avaliable.

If Byzantium takes a Pantheon or Follower belief as their bonus belief, then it makes the religion more desirable to have in your own lands, as you benefit from the bonus belief. If they're taking two Founder or Enhancer beliefs, then it's in your best interests to keep the religion at bay. Giving open borders to one of their religious rivals is one possibility if you lack a religion of your own.

Playing against Dromons

Dromons are highly powerful when attacking sea units, as such, don't attack Byzantium by sea until you at least have Galleasses. On the other hand, they're vulnerable to land-based ranged units, so if Byzantium's raiding you, pick up some Chariot Archers, Archers and/or Composite Bowmen and make them think twice about coastal raiding.

Playing against Cataphracts

For all their abilities, Cataphracts are still rely on horse resources. Take out the horses, and they have to disband units or get a massive combat penalty for not having enough of the resource.

Can't get to Byzantium's horse resources because of all those enemy Cataphracts in the way? Bring a few Spearmen. Cataphracts may be stronger than Horsemen but not enough to overcome the 50% bonus vs mounted units Spearmen have. And once you're on to Pikemen, they wipe the floor with Cataphracts.

A note about Ethiopia

Ethiopia's ability to rapidly claim a religion makes them a pain for Byzantium to face. And Ethiopia's UA gives them lots of defence, making it hard to invade them with a Cataphract war, or just in general, too.

Strategy by Style

Early-game Aggressors - Take some Spearmen with you when invading, and don't attack by sea. Taking them out early before they can get a religion is a reasonable idea, though you can safely leave them and attack them later, too.

Mid-game Aggressors - Take a couple of Pikemen or Lancers to account for remaining Cataphracts or Knights upgraded from Cataphracts. If attacking by sea, take Galleasses or better. Generally, they're little trouble.

Late-game Aggressors - Little difference from any other Civ.

Cultural Nations - Get plenty of culture in the midgame to defend against Sacred Sites. If you build plenty of wonders, (and/or you have a cultural UI,) you should be able to outproduce their tourism in the late-game.

Diplomatic Nations - Push through a rival religion as the World Religion, preferably one that belongs to a non-cultural Civ. Or your own religion, if you've got one. You could also try bribing a mid or late-game warmongerer to invade them, but you can do that to practically anyone.

Scientific Nations - Byzantium will likely fall behind in the tech race unless it's the core of their strategy. That leaves them vulnerable to invasion if they become a threat for victory in the mid-game. Be careful not to take too much, or else you'll lose the respect of other Civs.
Other Guides
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Meta-guides

These guides cover every Civ in the game and can be used as quick reference guides.

Civ-specific guides, in alphabetical order

All 43 Civs are covered in in-depth guides linked below. In brackets are the favoured victory routes of each Civ.
73 Comments
JD Vishnu 12 Nov, 2021 @ 8:39am 
Couple questions:
--Would the strategy still be the same in a multiplayer game?
--How wide is building wide? Should every other construction project in my capital be a settler? Are there benchmarks you keep track of as good references for when to build another settler?
W.R. Winter 25 Jun, 2020 @ 3:54am 
the early combination of Religious Texts/Itinerant Preachers/Unity of the Prophets actually shuts out other civs from the religion game completely, and at the cost of little to no faith. was stunned how powerful this was; by the end of Renaissance I had 100+ pressure in every city. with enemy prophets nerfed by half, there's no undoing that.

Byzantium might be underpowered overall but afaik they're the only civ capable of this.
Ciros 25 Feb, 2019 @ 5:01pm 
I never understood why Byzatines had the Cataphract as their unique unit. It wasn't, Cataphracts should be unique to an Iranian dynasty not greek...thieves!
Zigzagzigal  [author] 22 Oct, 2018 @ 9:16am 
Usually on higher difficulties it's too much of a risk considering how competitive the wonder is.
OhDee 20 Oct, 2018 @ 1:11pm 
Is it worth it to go for Stonehenge early on?
Zigzagzigal  [author] 1 Nov, 2016 @ 6:16pm 
Thanks.
WhiteCrow 30 Oct, 2016 @ 9:31am 
Love all your guides man. Very well written, and straight to the point. A+ work my friend.
Borzelena 5 Oct, 2016 @ 5:49am 
It was literally 1 tile outside of Shoshone cap vision. I have no idea how they didn't see it first.
Zigzagzigal  [author] 4 Oct, 2016 @ 4:45pm 
It's a coincidence but a nice one; El Dorado's a pretty good natural wonder to have around.
Borzelena 4 Oct, 2016 @ 7:18am 
For some reason every time I've played Byzantium in mp (2) I've spawned super close to el dorado. Felt like I should post this