Here's mine...well, the latest, anyway. Byzantines vs. Venice, and it was still quite early in the campaign, so it was a win-or-die situation. We both had roughly the same number of men, but they had all those badass Italian militia, while I had to struggle with crappy byzantine early era roster

So I thought that the smartest thing to do is to kill them off from a distance, thus bringing 6 archer units and 3 cavalry archer units. Apparently, I thought well

Here's the result:

The poor bastards never reached my battle line, being forced to charge uphill and getting shot by my missile troops in the process. Recipe: archer spam plus high ground plus dumb AI equals royal pwnage
Vhard, btw. Not that it mattered, though

And half of my losses were due to friendly fire, too...