Bloodiest Day: Few were aware of the destruction that was only seconds away as US air power was unleashed over Vietnam. May 20, 1972 was a day that would go down in history as the bloodiest of the entire war. Hell Over Hanoi: In the skies over Vietnam, every minute was a juggling act between life and death. Using dramatic reconstructions, we get in the cockpit of the F-4 Phantoms as they take on the notorious MiG-21.