During the Second World War, the city of Wuppertal suffered numerous Allied air raids, primarily nighttime attacks from the Royal Air Force's Bomber Command during the British-waged Battle of the Ruhr bomber offensive. Two of these air raids - on the night of May 29-30, 1943, heavy enough to cause a firestorm, and another barely a month later, on June 24-25, were the largest RAF bombing raids on the city. The wartime-era German Feuerwehr fire brigades were ill-equipped to fight these fires. The RAF's airstrikes destroyed areas of Wuppertal's northeastern Barmen, central Elberfeld and southeastern Ronsdorf communities, mainly through incendiary area bombing, resulting in destructive firestorms. Other Allied aircraft also carried out numerous smaller air raids on Wuppertal. Overall, more than 6,500 people lost their lives during World War II in Wuppertal from such raids; 38 percent of the built-up urban area was destroyed.
One of these RAF raids in February 1943 allegedly caused serious damage to the Goldschmitt adhesives firm, which was making "Tego-Film" wood adhesive for the German war effort - new aircraft designs meant to make large use of wooden airframe components, such as the Ta 154 and He 162 had their development seriously delayed or even temporarily curtailed as a result of the deficient replacement adhesive corroding the wooden airframes of such aircraft, resulting in crashes of the prototype airframes for both the mentioned Focke-Wulf and later Heinkel defensive fighter designs. The exact date for this especially critical RAF night raid is not a certain one; the progress on the Ta 154's development — which occurred nearly a year before the He 162's first prototypes were even built — and exactly when the corrosive replacement adhesive was first used for building its production airframe series, cause doubt concerning the early February 1943 timeframe.
The other factor that led to such high casualty rates in Wuppertal was its location. The city is located on the banks of two very steep granite riverbanks. The RAF had dropped timed explosives that caused the foundations of buildings to literally melt away.