Help with Orc Campaign Land of Knights

[Devean]

I had problems also, but then I managed to get a silver by selecting mostly heavy infantry, giving them the "Horse eaters" perk as soon as possible. That plus a siege machine, at least 2 skirmishers and 2 archers. First I attacked right, on the infantry on the hills with siege machines behind them. Then the knights standing near on of the fortresses came, and met my heavy infantry on the hills. This way I managed to finish them off without heavy casualties (careful positioning of archers and hexers was crucial). Then I captured the central forces and split my forces.
Ah, and I ignored the additional quest, too much distraction from the main quests.

I hope this helps.