John Joseph Gilligan Jr. was born on 17 June 1923 in Newark, New Jersey. He enlisted in the Marine Corps Reserve on 8 January 1942 and served at Parris Island, South Carolina, and Quantico, Virginia. Gilligan was mortally wounded in action while serving with the First Marine Raider Battalion at Tulagi, Solomon Islands, on 7 August 1942 and died the next day. For his heroism under fire, he was posthumously awarded the Silver Star.