Back in my Spanish campaign, I took Jerusalem in a crusade. I already had Antioch and Acre when the crusade was called, so I could get there quickly. When a spy showed that the city was minimally defended (1 general and 1 arab cavalry) I didn't bother with quality, only quantity. I went with a general, a bunch of turkomans, a couple of spanish units (I forget exactly what) and the rest was pilgrims and religious fanatics, with 2 units of unhorsed knights for muscle. I let the pilgrims do most of the dying, and captured the city. I moved the general and the turkomans out and left the remainder there to garrison the city, minimally reinforcing the garrison with some peasant archers and pavise crossbowmen brought in from Acre, and moved on.

Years later, still at war with Egypt, they show up with a full stack army to assault the city, and all I have is crap troops (2 religious fanatics, 5 pilgrims, 2 unhorsed knights, 3 pavise crossbowmen, 2 peasant archers, and the remaining 6 units spear militia). They have 2 generals, 5 units of tabardariyya, a unit of mamluk archers, 3 trebuchets, 2 catapults, and 7 units of saracen militia, and I have to defend the city. I decided not to try and defend the walls, as those are going to be crushed by all that artillery. I left the missile troops on the walls where they killed one general, then fell back to the square when they ran out of ammo. I used the rest to block the streets, pilgrims first, and left the unhorsed knights in side streets to hit flanks. In the end, I suffered horrendous casualties, but managed to kill their entire army and won the fight.