The massive military parade commemorating the 250th birthday of the U.S. Army, which coincides with President Donald Trump’s 79th birthday, was staged Saturday in Washington, D.C. The Sherman tanks, among the first in the parade, were extensively used in the European theater during World War II, rolled past Trump. World War II saw both Allied and Axis powers relying heavily on airpower to work with Sherman tanks and infantry on the ground to penetrate Axis lines. The Vietnam War was the first time helicopters were used in massive numbers in combat, leading it to be known as the “Helicopter War.” More than 12,000 helicopters were flown by the U.S. during the war, and seven will fly overhead as U.S. troops representing that conflict. The helicopters include the UH-1 “Huey,” which was used for everything from troop transport to medevac to supplies; the AH-1 “Cobra” gunship; and the OH-1 “Loach” – a daredevil helicopter whose crews scouted out enemy troops. The event is expected to include about 6,600 soldiers, 50 helicopters and 60-ton M1 Abrams battle tanks, as well as possibly 200,000 attendees and heightened security to match.