The Supermarine Spitfire was designed and developed in Southampton, evolving from the Schneider trophy-winning seaplanes of the 1920s and 1930s. Its designer, R J Mitchell, lived in the Portswood area of Southampton, and his house is today marked with a blue plaque. Heavy bombing of the factory in September 1940 destroyed it as well as homes in the vicinity, killing civilians and workers. World War II hit Southampton particularly hard because of its strategic importance as a major commercial port and industrial area. Prior to the Invasion of Europe, components for a Mulberry harbour were built here. After D-Day, Southampton docks handled military cargo to help keep the Allied forces supplied, making it a key target of Luftwaffe bombing raids until late 1944. Southampton docks was featured in the television show 24: Live Another Day in Day 9: 9:00 p.m. – 10:00 p.m.