I am playing campaign with Bavarians ( PMTW) and recently the Portuguese troops tried to lift a siege in Holland (new province)... with 6 men ( 1 militiaman, 2 Portuguese Sailors and 3 crossbowmen). Because I had over 650 men I annihilated them in time of few seconds.
Nice move, I had no artillery there and I had to move some cannons to prepare the assault, but the AI helped me a lot