At the beginning of the battle, the game automatically manages the number of squares where troops can be placed. I happened to lose battles because, even having a lot of units, the game gave me a few placement boxes (even though we were in open field). It would be more tactical if the number of squares were proportional to the type of movement of the troops. 
For example, if I put the troops "on march", I could receive a bonus to movement but a penalty to the number of placement squares, in a possible battle. Conversely, if the troops are stationary, or moving slowly (movement penalty), I should receive a placement bonus.

Thanks for your support!

This is another aspect which heavily favors the attacker.

So I do think there needs to be more benefit to being on defense - for example, ability to position your own flag and your suggestion more spaces for defense.

I hope battle management is the next big overhaul. Because to be honest, it's already fun, but they can improve it to eliminate many of these complaints.