I once almost had a successful crusade from the HRE. It was permitted rather easily through Constantinople, and I could see really quickly why: Egypt had these AMAZING armies with high ranking generals and large numbers of troops, sometimes numbering well over three thousand. My little crusader group had barely half that, although the troops were of high quality, and the general was exceptional. The crusade managed to bust through three large and powerful armies. One battle had an epic scene where mere archers, spearmen, and peasants were held up on a hill, with their flanks being protected by only a few armored units.

As the enemy, who was in every way possible superior, approached, my army waited. As the enemy set foot on the hill my rabble charged down the hill. A moment later, heavy cavalry charged from a forest, and cleared the rear guard and then proceeded to charge into the rear.

The last army was much larger than average, but jagged and depleted. The battle was on a hill, but the enemy closed in too quickly for a downward charge. The enemy general was in front. As he approached my archers let fly their arrows. The first volley killed him off, and caused the enemy's flanks to rout. My army charged and destroyed the enemy formation. Then, it was about to cripple the last wave, when I noticed that some armored troops were still idle! I charged them into the enemy, but it was too late. With no support or advantage, the weaker troops failed and fled. The crusade was over.

It was fun though. Oh, and I took Flanders that year, so it's all good. You just have to pick a good time, that's all.