The term "thousand-bomber raid" was used to describe three night bombing raids by the Royal Air Force against German cities in summer 1942 during World War II.[1] The term was a propaganda device, whereby Arthur Harris included the relatively few modern four-engined "heavy" bombers that were currently operational, but mostly 1930s-era twin-engine "medium" bombers and many otherwise unsuitable small bombers and trainee aircrews in the raids to accumulate a force of 1,000 bombers as a demonstration of the RAF's growing power. Later RAF raids concentrated on effectiveness rather than sheer number, with raids of 400-700 four-engined bombers occurring, but the number of 1,000 not being claimed again.