You don't win with tactics in this game. You win cavalry battles depending on the individual skill of your members and that your members get a clean charge on the enemy - rather than being charged in the back, or having a bad charge angle. That's it.
There's only a few guidelines which can keep players generally longer alive, but really, that's it.
Isn't this what this thread is about? Whats is a "clean charge" and how to employ it properly.
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Generally linebattles's are my opinion are centered around artillery and thus have disappointingly few tactical decisions involved.
1. The team with the better artillery position has an advantage
2. The team who keeps their artillery alive has an advantage
3. The team who keeps their lines from meeting and unfortunate end by a cannonball has an advantage.
Of course there is a lot of manouvering and tactics going on initially but in battles the primary goal is in my opinion always to take out the enemy artillery.