The civil war
This picture represents the battle between brothers, the Civil War. On the left it shows a union soldier and waving behind him, the American flag. On the right, A confederate soldier standing in front of the Confederate flag. Even though i don't think it was intentional, this can also represent (a little exaggerated) the closeness in which some of the battles took place, literally face to face and sometimes hand (or bayonet) on hand combat.