<p>Early missions against oil were experimental; not all Allied leadership was convinced of the strategic benefits that Spaatz and the Americans argued would accrue from bombing German oil processors. Proof came soon. The Eighth sent well-escorted 935 heavy bombers to the Ruhr on 12 May. More than 800 reached and bombed the primary targets. All were damaged, and some were hit heavily. There was an unintentional bonus; one of the buildings hit at Merseburg-Leuna contained the laboratory where heavy-water experiments were being done as part of Germany's nuclear weapons research. Aggressive attacks by more than 150 Luftwaffe fighters shot down 46 bombers and 10 fighters, but lost many of their own in the combat.
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<p>By striking at the production of refineries and synthetic fuel plants, the USSTAF drew the Luftwaffe up to fight, and to lose. By then, every single loss was critical to the Germans, because in mid-May, for the first time, Luftwaffe pilot losses exceeded the available replacements.
