The Sheffield Blitz is the name given to the worst nights of German Luftwaffe bombing in Sheffield, England, during the Second World War. It took place over the nights of 12 December and 15 December 1940.
In 1940 Sheffield was a city of about 560,000 people and contained many heavy industries, primarily centred on steel and armaments. Hadfields steelworks was also the only place in the UK at that time where 18-inch armour-piercing shells were made. Most of the factories were located in the East end of the city beside the River Don. Documents captured at the end of the war showed that the targets for the raids included the Atlas Steelworks, Brown Bayley Steelworks, Meadowhall Iron Works, River Don Works, Darnall Wagon Works, Tinsley Park Collieries, East Hecla Works and Orgreave Coke Ovens.
The full moon was on 14 December 1940 and both blitz nights were cold and clear.
The German code name for the operation was Schmelztiegel ("Crucible").
On the afternoon of 12 December British monitoring stations detected X Verfahren (sometimes called X-Gerät) radio beams being laid across northern England and calculated that the likely target of the coming raid would be Sheffield.
The yellow alert was received at 6.15pm followed by the purple alert at 6.45pm. The red alert was sounded at 7pm. The attack was made by three main groups of aircraft flying from airfields in northern France, including Cambrai. 13 Heinkel 111s from Kampfgruppe 100, the German Pathfinder unit arrived over the city at 7.41 p.m. and dropped 16 SC50 high-explosive bombs, 1,009 B1 E1 ZA incendiaries and 10,080 B1 E1 incendiaries. The first incendiaries were dropped over the suburbs of Norton Lees and Gleadless.