On this day in 1942, a thousand-plane raid on the German city of Cologne is launched by Great Britain. Almost 1,500 tons of bombs rain down in 90 minutes, delivering a devastating blow to the Germans' medieval city as well as its morale.
Air Marshal A.T. (later Sir Arthur) Harris, commander in chief of the Bomber Command, planned Operation Millennium. It was his goal to prevent significant losses of Royal Air Force bombers by concentrating air attacks in massive bomber raids, overwhelming the enemy by numbers and delivering decisive, crippling blows. Harris would need to beef up the relatively small number of 416 "first line" aircraft needed, though; to those he had to add second-line and training squadron bombers, thus creating an aircraft force of 1,046.
On the night of May 30, Cologne was besieged: 600 acres of the city sustained heavy damage, 45,000 Germans were left homeless and 469 were killed. The chemical and machine tool industries, the main targets of the raid, were rendered useless. The cost to the British: 40 bombers, or less than 4 percent of the total that participated.
British Prime Minister Winston Churchill, who approved the raid, telegraphed President Franklin Roosevelt the next day: "I hope you were pleased with our mass air attack... there is plenty more to come."