The City of Cologne

Cologne

Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...

 was bombed in 262 separate air raids by the Allies

Allies

In everyday English usage, allies are people, groups, or nations that have joined together in an association for mutual benefit or to achieve some common purpose, whether or not explicit agreement has been worked out between them...

 during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

, including 31 times by the Royal Air Force

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 (RAF). Air raid alarms went off in the winter/spring of 1940 as enemy bombers passed overhead. However, the first actual bombing took place on 12 May 1940. The most notable attack on Cologne was the first Allied 1,000 bomber raid on 30/31 May 1942.
The first 1,000 bomber raid by the RAF was codenamed Operation Millennium, Cologne was chosen as the target and the raid took place on the night of 30/31 May 1942.