In the historical battle of Ausculum (Rome vs. Epiros) which I played as the romans, I was winning quite convincingly... in the end, there remained just a single formation of Phalangitai, who stood facing the forest at the left side of the battlefield... I gathered all units of Principes, Hastati and leves I had left and surrounded them. The Epirotes kept facing the woods, while my legion formed in their rear and flanks. they kept facing the woods, turning phalanx mode on and off and on and off again untill all my units were in place. Then, I charged at them, and they still did not change facing....

needless to say, they all died.