The Alexander expansion. Greece and Babylon.

Good day. I'm playing the Greece and Babylon campaigns. I've maxed out Alexander's skills in the second map, focusing on Death and Chaos magic; initially, he had Warrior skills and Upkeep. I'm facing huge computer-controlled armies. I've replayed several times, but sooner or later, the computer forces me out of my home city, and that's it. I'm not very successful at wearing down the computer; the computer players don't fight each other, so after defeating one, I stumble upon another. What tactics can you suggest? I've been spending a couple of weeks on this in the evenings.