Belisar, I once had a stack of 23 Knights - that was the best that I could in any way muster on a tiny map - attack two regular Pikemen and one Longbowman in an AIs last city. Leonardos was in there, I had the money to mass upgrade the remaining troops (I was hoping for 15 surviviors) the Cavalry (whihc the other AIs didn't know yet), then blaze through my continent...... That would have been my first deity win! A big one, too!
After my attacks (15 dead Knights!), one Pike had 1 HP and the LBM had 3 HP left - lost 1, promoted, lost 1.
Three Spears(!) and 1 LBM froma different city counterattacked my retreated Knights, blocking their escape route. The next turn, they all 4 did it again. Not one, not even a sginle one of my Knights made it abck home.
2 turns later 15 AI Cavs killed my three Muskets in my capital. End of game.
Yes, I hate the RNG, and yes I worry a lot about it!