Well, my favorite moments was playing with either the French, the English, or Russia. When I played the English, I managed to have revolts that were led by Robin of Locksley (Robin Hood) and William Wallyce (William Wallace). I crushed Robin Hood's forces easily (they consisted mostly of Sherwood Foresters), but William Wallace was a 6 star general to start off with I think. I took back Scotland in 3 or 4 battles, but it was magnificant.
When I was the French it was crusade city and I played all the way from 1095 A.D to the end of the game in 1453 A.D. I took over Byzantine and all the territory surrounding. I took over controll of the Balkens, and managed to successfully repel the Mongol onslaught. I didn't try to win the game, because I wanted to have somone challenge me from start to end. The last half of the Campaign, I was fighting in Northern Africa and the Middle East. I was facing mostly the Egyptians and the Almohads. I was allied with the Pope most of the way through, until they were conquered and I had to go rescue Italy from those damn Sicilians.
I had lot's of fun fighting around the Prussia area a bunch of times when I was the Russians. I had a few cool battles with the Mongols.
But my personal favorite battle was the Pope's forces against mine. Well, I had occupied the Papal States and Rome for more than a hundred years prior to the battle. I easily crushed each and every Pope's forces that tried to rise up against me. I had gathered an army of 44,000+ and they were stationed in Central Italy. It cost a bitch load of cash for the upkeep, but they were mostly veteren soldiers. Anyways, the Pope finally faced me with an army of 21,000+ soldiers. It actually took me most of the day to finish the battle. I think the timer was originally set at 450 minutes. I finished towards the very end with less than one tenth of the timer remaining. I killed 11,500 men while capturing over 4,000 troops. About 7,000 of my men were killed in action while only less than 400 were captured.