I know there are a lot of threads about idiotic AI and what not, but I feel mine is a special case.
....So I go to defend my protectorate Hannover from the Dutch invasion force.
The United Provinces' troops consist of mostly line and oddly enough grenadier units with 100 men (never seen that but oh well)
They have the usual AI obsession with Puckle Guns (Almost every European nation in my campaigns have recruited armies of puckle guns... because they are so awesome*sarcasm*

)
Thats when things got, may I say it, mentally challenged.
The Puckle guns began firing at the ground where the Dutch troops were, and they just paced back and forth for about ten minutes soaking up lead balls from their own rapid firing goodness.
I just sat and watched in amazement as they killed their own general and even routed a light infantry company.
Then the puckle guns fired on each other and destroyed half of them before finally someone with a brain said "Hey look its the Prussians! Lets go get them"