Sergeant Meagher was a medic with the Medical Company, 8th Cavalry Regiment, 1st Cavalry Division. He was listed as Missing in Action while tending his wounded comrades near Unsan, North Korea, on 2 November 1950. He was presumed dead on 23 February 1954. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Meagher was awarded the Purple Heart, the Combat Medical Badge, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.