Iserlohn was a 4,667 GRT cargo ship that was built in 1909 by Reiherstieg Schiffswerfte & Maschinenfabrik, Hamburg, Germany. She was ceded to the United Kingdom in 1919, passing to the Admiralty. In 1921, she was sold into merchant service and renamed Union City. She was sold to Finland in 1924 and renamed Wasaborg. In 1935, she was sold to Italy and renamed Erica. In 1940, she was seized by the United Kingdom and passed to the Ministry of War Transport (MoWT). Renamed Empire Defiance, she served until June 1944, when she was sunk as a blockship at Sword Beach, Ouistreham, France in support of Operation Overlord. She was salvaged in 1951 and scrapped at Antwerp, Belgium.