RAF Launches the First 1,000-Bomber Raid

On the night of May 30-31, 1942, Britain's Royal Air Force mounted Operation Millennium, the first thousand-bomber raid in history, against the German city of Cologne. Air Marshal Arthur Harris of RAF Bomber Command assembled the unprecedented force by drawing on training and reserve units to reach the symbolic figure of a thousand aircraft.

The bombers dropped roughly 1,455 tons of explosives on Cologne, the majority of it incendiary, igniting widespread fires across the city in a concentrated stream of aircraft designed to overwhelm the defenses. The cathedral survived, but large areas of the city were burned out.

The raid demonstrated that the RAF could deliver massive, concentrated blows and marked an escalation toward the sustained area-bombing campaign that Bomber Command would wage against German cities almost nightly through the remainder of the war.