The B-17 Flying Fortress was perhaps the most well-known American heavy bomber of the Second World War. It achieved a fame far beyond that of its more-numerous contemporary, the Consolidated B-24 Liberator. The first pre-production Y1B-17 Fortress was delivered to the 2d Bombardment Group, Langley Field, Virginia on 11 January 1936; the first production B-17B was delivered on 29 March 1939 also to the 2d Bombardment Group. A total of 12,677 production Fortresses was built before production came to an end. In August 1944, the B-17 equipped no less than 33 overseas combat groups.