In March 1944 the "Plan for Completion of Combined Bomber Offensive" was put forward which found favour with the British Ministry of Economic Warfare. The plan proposed attacking "fourteen synthetic plants and thirteen refineries" of Nazi Germany. The plan estimated Axis oil production could be reduced by 50% by bombing—33% below the amount Nazi Germany needed—but also included 4 additional priorities: first oil, then fighter and ball bearing production, rubber production, and bomber output. The damage caused by the 12 and 28 May trial bombings of oil targets, as well as the confirmation of the oil facilities' importance and vulnerability from Ultra intercepts and other intelligence reports, would result in the oil targets becoming the highest priority on 3 September 1944.