Following the Rotterdam Blitz of 14 May, RAF Bomber Command was authorized to attack German targets east of the Rhine on 15 May; the Air Ministry authorized Air Marshal Charles Portal to attack targets in the Ruhr, including oil plants and other civilian industrial targets which aided the German war effort, such as blast furnaces (which were visible at night). The first attack took place on the night of 15/16 May, with 96 bombers setting off to attack targets east of the Rhine, 78 of which were against oil targets. Of these, only 24 claimed to have found their targets.