The phrase "going over the top"; OTT, came into usage during World War I Iand referenced attacking infantry rising out of their own trenches to assault the enemy. When the whistle blew and in order to attack opposing trench lines, infantry were required to climb over the parapet of their trenches and cross No Man´s Land""." As World War I offensives generally sustained heavy losses, "going over the top" was an unpopular activity for soldiers.