First Lieutenant David Waybur was born on 29 September 1919 in Piedmont, California. He worked as a grocery store clerk and ranch hand before joining the military. Waybur enlisted in the Army as a private on 22 November 1940 and earned his commission through Officer Candidate School. By the time of the Allied invasion of Sicily in July 1943, he was a first lieutenant commanding the 3rd Reconnaissance Troop, 3rd Infantry Division.

On the night of 17 July 1943, one week after the invasion of Sicily began, Waybur volunteered to lead a reconnaissance patrol into enemy territory near Agrigento in order to locate a missing Ranger unit. The patrol, consisting of three Jeeps, was cut off and attacked by four Italian tanks. In the ensuing firefight, Waybur and three of his men were wounded, Waybur seriously so. When the patrol's three machine guns ran out of ammunition, he ordered his men to take cover and single-handedly disabled one tank by standing in the open and killing its crew with a Thompson submachine gun. After sending one patrol member to get help, Waybur continued to lead his men in holding off the three remaining tanks through the night. American reinforcements arrived in the morning, and the Italian tanks withdrew. Three months later, on 21 October, Waybur received the Medal of Honor for his actions during the battle. The medal was formally presented to him by Lieutenant General Mark Wayne Clark, commander of the Fifth Army, during a ceremony in North Africa later that year.

Waybur was sent back to the United States to work on war bond tours, but he eventually asked to be returned to combat duty. He was killed in action in Germany on 28 March 1945, two years after receiving the Medal of Honor. Waybur was buried at the Lorraine American Cemetery and Memorial in Saint-Avold, France.