John Vincent Power was born 20 November 1918 in Worcester, Massachusetts. He was educated in the local schools and graduated from Classical High School in 1936. He graduated from Holy Cross in 1941, where he participated in tennis, basketball, football, and golf.

He enlisted in the Marine Corps Reserve on 7 July 1942, and was soon assigned to Officers' Candidates School. He was commissioned a second lieutenant in the Reserve on 31 October 1942, and entered the 14th Reserve Officers Class at Quantico, Virginia, for a two-month course of instruction.

In January 1943, 2dLt Power joined Company E, 3d Separate Battalion, and deployed with that unit in March to Camp Pendleton, California. The designation of his unit was changed to Company K, 3d Battalion, 24th Marines, and the unit subsequently joined the newly-formed 4th Marine Division. He was promoted to first lieutenant on 31 August 1943.

First Lieutenant Power sailed with his unit in mid-January 1944 from San Diego harbor, and on 1 February, the 24th Marines participated in the assault at Roi-Namur in the Kwajalein Atoll, Marshall Islands. Roi was conquered in short order and the surviving Japanese fled to nearby Namur. It was during the battle of Namur Island that 1stLt Power was killed in action and posthumously awarded the Medal of Honor, when he charged a Japanese pillbox despite a severe stomach wound.

The Medal of Honor was presented to his parents by President Franklin D. Roosevelt at the White House in November 1944.

First Lieutenant Power was initially buried in the 4th Marine Division Cemetery on Roi-Namur, Kwajalein Atoll. His remains were later returned for burial in St. John's Cemetery, Worcester, Massachusetts.

Power's official Medal of Honor citation reads:

For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty as platoon leader, attached to the 4th Marine Division, during the landing and battle of Namur Island, Kwajalein Atoll, Marshall Islands, 1 February 1944. Severely wounded in the stomach while setting a demolition charge on a Japanese pillbox, 1st Lt. Power was steadfast in his determination to remain in action. Protecting his wound with his left hand and firing with his right, he courageously advanced as another hostile position was taken under attack, fiercely charging the opening made by the explosion and emptying his carbine into the pillbox. While attempting to reload and continue the attack, 1st Lt. Power was shot again in the stomach and head and collapsed in the doorway. His exceptional valor, fortitude and indomitable fighting spirit in the face of withering enemy fire were in keeping with the highest traditions of the U.S. Naval Service. He gallantly gave his life for his country.