What ambush mechanic that’s in the game already is when an enemy company will hide out of your company’s LOS on the main map until they move in to commence battle, like hiding in a tree line by the road for example. At that point, your men know they’re being attacked that’s why the AI knows where your men are even if you don’t get seen in the FOW. You can get free attacks if the enemy is already moved into one of your brothers zone of control and tries to move around within said zone. The only time I’ve seen someone been able to attack someone that steps in their zone of control are enemies armed with a spear and do spear wall formation prior.
I am not really sure what you are saying here, but thanks for your comment.
A wise general wins before the battle, while the ignorant general must fight to win - Zhuge Liang