I just finished only my 3rd complete win in BtS with Justinian (Domination Victory in 1860AD; settings = Prince, Epic, Large, Big and Small, Low Sea Level, 11 AI Civs). It was a blast!
Basically, I started slowly, grabbed enough space for 6 cities (including the essentials for my UU [and UB], Horses and Iron), and was teching with all haste towards Guilds when a neighbor attacked, and then while fighting him off, another attacked, and so on.
Usually, I hate being at war for a long period of time (I'm usually 70% builder, 30% war-monger), but in Justinian's case, I didn't mind because:
1. For defensive wars, Hippodromes + Horses + 10% Culture slider = no WW. For offensive wars, you'll still get WW, but much less than usual.
2. With that Imperialistic trait, I really started racking up the Great Generals. Usually, I make a few Warlord units, but in this case, I resisted the temptation and settled all of mine in my military factory. By the end of the game, I had
10 GG's settled there. With West Point, Barracks, Vassalage, and Theocracy, I was cranking out new units that had
31 XP!!! A thing of beauty, it was.
3. Once I finally got Guilds, the Cataphracts showed their awesomeness. Going against fortified Longbows was still not a picnic, but if all I had were Knights, I would have been stuck lugging Maces and Trebs like the rest of you plebs
. The funny thing about them was that, since in my game I got them quite a bit later than I was originally planning, I was initially disappointed with their performance. But as time went on, and the survivors piled up the XP, I ended up with a huge cadre of highly promoted Cataphracts, that nicely upgraded into killer Cavalry as the game wound down. And there was no need to upgrade to Cuirassiers in the middle, because, in essence, Cataphracts already
are Cuirassiers.
So, that's my take on the Byzantines. Mind you, I'm far from an expert and played "sub-optimally" for most of the game, but Justinian's still a hell of a lot of fun if you get some momentum. To my mind, he's one of the best momentum leaders out there.
Three words of advice: Horses, Iron, Guilds.
That's all you have to know. Oh, one more - WAR!
. Use the Imperialistic trait to ensure that you get enough settlers out to secure both iron and horses. Then pick up drama for the hippodrome and head straight for guilds. Cataphracts are just amazing 
, and with the hippodrome war weariness is simply not a problem 
.
s to get the most out of the IMP trait. Usually this means Mining/Bronze Working and whatever food techs let me improve my capital's BFC. If I don't have it already, I then get Animal Husbandry to see Horses, the Iron Working for Iron.
, considering the way this whole 3.13 information issue played out in this forum. From the community's 
perspective Firaxis' strategy can indeed be termed "Byzantine".
