Cologne (Köln) was the first German city to experience a "1,000-bomber raid" by the Royal Air Force during the Second World War (1939-45). The attack took place on the night of 30 May 1942 and was planned as a demonstration of the destruction a large force could do using the strategy of area bombing over a short space of time.
This is a companion discussion topic for the original content at https://www.worldhistory.org/article/2410/the-thousand-bomber-raid-on-cologne-in-1942/.