A native of Cincinnati, Ohio, Lupo delivered newspapers before being drafted in October, 1917, along with hundreds of thousands of other young American men after Congress declared war on Germany at the behest of President Woodrow Wilson. With only a fifth grade education, he arrived in France in March, 1918, and was assigned to the 18th Infantry Regiment of the U.S. 1st Infantry Division. On July 20 his battalion took part in a French-led attack on a German-held salient near Soissons. Lupo fell in combat on that same day and was hastily buried on the battlefield, in the same grave with another U.S. soldier.