Ozbenno said:
When you say poor resource wise, did you have any metal or horses (you must if you had Cossacks).
I mean I only had 1 deer, 1 wheat and stone in the BFC, rest was four grass forests, a bunch of plains forests, some hills and even some regular unforested plains. Not exactly a prime OCC spot.
I did have horses for cossacks, but no other strategic resources. Funny how IW is pretty much a dead end tech, and I only researched it fairly early because I had those unforested tiles that may have had some iron

Otherwise I might delay it until after gunpowder at least. Same with AH if no sheep.
The way to win this (if going for OCC/conquest) is to realize that you cannot afford to lose troops on a regular basis if you are ever going to "break out". You will need a defensive force for a long time that will kill intruders at 95%+ odds. This can be done with fast muskets if you station them so that you can attack enemies on non-defensive terrain, while you stand on forest/hill/fort/whatever.
Once you can kill stacks with no losses, you can start reaching quantities to actually send out stacks strong enough to wipe out civs. Rifles are a safe bet if you tech fast enough, trebs to bombard culture is good, as these AI tend to have quite a bit of it, and you want to avoid losses if possible, 80% odds should feel uncomfortable on attack. The offensive stacks should have one purpose, to raze cities. Ignore stray units and other things, unless you can kill a settler. Try to carve a path through their core cities first to cripple them. They will quickly resettle lost sites at first, but they cannot keep up if you keep razing cities.
The AI techs slowly on this map, so you can easily have rifles vs longbows for a long time. And always remember the GG medic.
Wonder spam as much as possible early on. Chicken Pizza is actually a great build to deny the AI the bonus.