The choice to not target the assembly areas for Operation Overlord meant that there was no significant impact on the allied time table for the invasion. The raids were ironically to prove more costly regarding German military capability than for the British, draining the Luftwaffe of irreplaceable aircrew and some contemporary aircraft and thus reducing the potential offensive air response to oppose Operation Overlord. After the failure of this conventional bombing campaign, the Nazi leadership sought unconventional ways to attack Britain.