The most famous of all Avro military aircraft and without doubt the most successful heavy night bomber to be deployed over Europe during World War II. Beginning active service in 1942, the Avro Lancaster was a British four-engined heavy bomber made initially for the Royal Air Force. Along with the Halifax, the Avro Lancaster shared the major burden of Bomber Command's prolonged night offensive over Germany. Primarily a night bomber, the Lancaster excelled in diverse roles including daylight precision bombing. The Lancaster gained worldwide fame as the "Dam Buster" used in the 1943 Operation Chastise raids on German dams in the Ruhr valley and sinking the Bismarck-class battleship Tirpitz in a Norwegian fjord. Powered by four Rolls-Royce Merlin engines giving a top speed of 287 mph and a range of 1,660 miles, the Lancaster’s’ seven-man crew could provide a knockout punch with a typical load of 18,000 pounds of high explosive over the target.