OOC: I was thinking of..
The phalanxes of the King hold the Orcish assault, but, barely. Then Nicanor blows on his horn to give the sign to the hidden cavalry to strike from the flank into the Orcish Lines, which shatters them. However, the Orcs notice it and start shooting them down with crossbows, and the cavalry loses much of men when it charges into the flank, not having completely the effect Nicanor wanted, and the line holds stand. After a huge battle then they both retreat.