Army Group A was tasked with capturing a production center of this resource during (*) Case Blue, a German offensive that resulted in the Battle of Stalingrad.
A firm named BRABAG was established to produce a synthetic substitute for this resource. The name "Black Sunday" was given to the day of Operation Tidal Wave, an air attack on several plants that processed this resource near the Romanian city of Ploieşti ("ploy-ESHT"). Army Group A was tasked with capturing a production center of this resource during (*) Case Blue, a German offensive that resulted in the Battle of Stalingrad. Fred Koch, the namesake of Koch Industries, helped build plants that processed this resource in Nazi Germany and the Soviet Union. Baku was a major Soviet production center of this natural resource. For 10 points, name this natural resource, a liquid that one might refine in order to produce fuel for airplanes and tanks.
A firm named BRABAG was established to produce a synthetic substitute for this resource.
crude oil [or petroleum; prompt on fossil fuels; anti-prompt on gasoline, diesel fuel or other things that are derived from crude oil]