HMTS Monarch, launched on 8 August 1945 and completed during February 1946, was the fourth cable ship with that name. The ship was built for the General Post Office (GPO) for the laying and repair of submarine communications cable and was the largest cable ship in the world when completed and the first cable ship to have all electric cable machinery. The ship was first engaged in repair and update of existing cables which had been neglected during the war. Monarch laid the first transatlantic telephone cable TAT-1.