This was the map I mentioned being previously stuck on. Then I drew Angmar, and took the AI to town. They were Gondor, and no match for the might of the Witch-King. It’s strange to me what races I win with on what maps. Most unpredictable. 
I have a good strat with Angmar which blends a great deal of wights in with black numenorians. The wights and heroes make a front that’s hard to break. My only problem is with large sums of archers, they take out my wights pretty quick, and without their debuff and power, the numenorians don’t last on their own. 
I’ll keep you posted the next time I get stuck.