What Are the Optimal Ranks for Units?

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I deploy my Janissary Heavy Infantry in ranks of 5, I assume this would work with sword infantry too. In MTW I used to do 4, but in M2 5 ranks seems reasonable with the improved cavalry. This way, enough Janissaries always survive to fight or defeat the cavalry, or at the very least hold them there long enough for my own heavy cavalry to flank.

Musketeers and archers I deploy in ranks of three. I believe that was the MTW optimum deployment too, so I just carried it over. This is very weak for melee, so if you're using horse archers, make sure to form them in thicker ranks (I usually do 4) before charging.

Cavalry I deploy in ranks of 4. 3 makes the line too thin, and it's easy to break with infantry. 4 ensures that there is enough momentum to break the line but still enough horses to keep fighting if the first rank is killed. This also makes it easier to break them off and recharge, since less of them are exposed and thus less will die when they turn their backs to reform. With 5 ranks, not enough men are fighting and thus it turns into a meat grinder where one rank is killed, the next advances, that is killed, etc.