September 13th. 1944: Ten bombs destined for the Monowitz Industrial Complex were dropped over the Birkeau cremation buildings (5 km to the west of Monowitz).  
 

At any time from April to December, 1944, Mosquito twin-engined fighters, could have flown undetected at 9,000 metres (30,000 feet) elevation, and swooped down to bomb the Birkenau cremation buildings, or other buildings, at tree-top height. At 4,000 hp, Mosquitos were capable of out running any German fighter until the advent of the jet propelled ME-262 fighters in late 1944. This type of 'pin-point bombing' raid had been successfully used in operations such as the Amiens, France prison raid on February 18th, 1944, where inmates, who were scheduled for executions starting February 19th, escaped through holes blown in the prison walls.