In December 1965, Father Capodanno received his commission as a lieutenant in the Navy Chaplain Corps. He was assigned to the First Marine Division in Vietnam in April 1966.

At 4:30 am, September 4, 1967, during Operation Swift in the Thang Binh District of the Que Son Valley, elements of the 1st Battalion 5th Marines encountered a large North Vietnamese unit of approximately 2,500 men near the village of Dong Son. The outnumbered and disorganized Company D was in need of reinforcements. By 9:14 am, 26 Marines were confirmed dead, and another company of Marines was committed to the battle. At 9:25 am, the commander of 1st Battalion 5th Marine requested further reinforcements.

Father Capodanno went among the wounded and dying, giving last rites. Wounded in the face and hand, he went to help a wounded corpsman only yards from an enemy machine gun and was killed. His body was recovered and interred in his family's plot in Saint Peters Cemetery, West New Brighton, Staten Island, New York.

On December 27, 1968, Secretary of the Navy Paul Ignatius notified the Capodanno family that Lieutenant Capodanno would posthumously be awarded the Medal of Honor in recognition of his selfless sacrifice. The official ceremony was held January 7, 1969.

Source: Order Sons of Italy in America, Fr. Vincent R Capodanno Lodge #212