Elijah Bruen was mustered into the 7th New Jersey Volunteer Infantry, Company K on January 23, 1862. He served through several battles and campaigns, re-enlisting on February 14, 1864 where he was transferred to Company D. He served through the duration of the war, succumbing to typhoid fever near the end. He was furloughed to battle the disease and died at home on June 7, 1865.

He is buried in Hillside Cemetery in Madison, New Jersey.