What is a good army makeup if my nation can make heavy infantry, horse archers and cavalry? A good mix of all 3? Any thoughts would be appreciated! 
What is a good army makeup if my nation can make heavy infantry, horse archers and cavalry? A good mix of all 3? Any thoughts would be appreciated!![]()
Or you could go horse crazy. I get tremendous results with 2 parts cavalry, 3 parts horse archers.
The Good: Your armies fly all over the map and have good inherent bonuses against most of the soldier types you'll fight. Rapid and strong response to barbarian hordes and risings.
The Questionable: Expensive compared with foot armies (I still find the bang for buck makes them eminently affordable).
The Bad: The only annoying thing I encounter with mounted armies is that they have no ability to assault enemy cities. They can still siege a city into surrender, even rather quickly if you move in with overwhelming numbers and a good commander, and they fight well against enemies trying to break a siege, but you will still need extra patience when wrapping up a big war.
My general tactic with mounted armies against strong opponents (and this presumes I have at least four or five provinces and ideally a border with a stockade or better) is to play defense at first, let them weaken themselves a bit through attrition and assaults. Try to attack before you lose a province, but it's not a disaster if you lose one or two in the beginning. Move in with your best commander, throw back the enemy, and beat that retreating enemy to its destination. Chase that army until it's annihilated. Wash, rinse, repeat until you feel the enemy's manpower has shrunk enough that you can suppress their armies with just one or two of your mounted armies. Send the rest of your mounted armies to siege. It may even be expedient if you break your sieging armies into armies with the minimum soldiers necessary to besiege enemy provinces (in other words, you can carry on more sieges at the same time).
If you lose a province or more in the beginning of this tactic and need every last mounted unit to fight your opponent, simply raise a few cheapo infantry militia units and park them on your captured provinces. You don't even need to give these militia forces a commander. As long as their armies are just big enough to siege the province, you'll usually take it back pretty fast.
Have not tried that "all cav" approach. If you are not playing one of the pastoralist tribals (are Mongols or their ancestors in this game?) it strikes me as a little bit ahistorical for the mediterranean or European societies represented to build all cav, or even majority cav forces.