|January 20, 1867– February 10, 1930 (aged 63)|
|Place of birth||Bergen, Norway|
|Place of death||Brooklyn, New York|
|Place of burial||Cypress Hills National Cemetery|
|Allegiance||United States of America|
|Service/branch||United States Navy|
|Years of service||1889-1925|
|Unit||USS Missouri (BB-11)|
|Awards||Medal of Honor|
Warranted gunner in 1904, he was serving in USS Missouri (BB-11) April 13, when a charge ignited while a 12‑inch gun was being loaded for target practice. Eighteen officers and men lost their lives. Monssen entered the burning magazine through the scuttle and threw water on the fire with his hands until a hose was passed to him. For his actions he was awarded the Medal of Honor.
He was commissioned lieutenant in July 1918 and he retired December 15, 1925.
Rank and organization. Chief Gunner's Mate, U.S. Navy. Born: January 20, 1867, Norway. G.O. No.: 160, May 26, 1904.
See USS Monssen for the two ships named in his honor.