Rival contingents on the same side may fight each other when they come close.
How it works
When Orcs of the Red Eye and Orcs of the White Hand come within 4" of one another a die is thrown: on a 1 they fight each other (before any other melees are resolved); on 2-6 they follow their original orders.
when ORCS OF THE RED EYE & ORCS OF THE WHITE HAND approach within 4 inches of one another, 1 die is thrown to see how they react.