gah, I was, I think Spanish, against the Russians, and they were defending. They had way more troops in reserve than I did; after they camped at the very damn edge of the map, and I had to march my troops over hills and valleys for a few looong minutes (with CTRL-T on, ofc), right before I got in range of their archers, they turned their backs on me and all ran away !
I mean, wth ? And I wasn't doing anything fancy such as flanking or surrounding them or anything, just coming straight at 'em.
I must have had a really ugly general...