During the Second World War, Hamburg suffered a series of Allied air raids and which devastated much of the city and the harbor. Then it was the most important port of continental Europe, and the largest shipping center in the world. There were tremendous ship building yards and vast oil storage installations. The oil refineries on south side of the Elbe were targets of the 392nd Bombardment Group. On 23 July 1943, Royal Air Force and United States Army Air Force firebombing created a firestorm which spread from the main railway station and quickly moved south-east, completely destroying entire boroughs.
Thousands of people perished in these densely populated working class boroughs. The raids, codenamed “Operation Gomorrah” by the Royal Air Force, killed at least 42,600 civilians. About one million civilians were evacuated. While some of the boroughs destroyed were rebuilt as residential districts after the war, others were entirely developed into office, retail and limited residential or industrial districts.