Thursday, June 10, 1943. Pointblank
The Pointblank Directive was issued by the Allied Combined Chiefs of Staff directing the implementation of Operation Pointblank, the round the clock Allied bomber offensive over Europe. The order prioritized targets for the combined Allied air forces, starting with the German aircraft industry.
The order met with passive resistance from RAF's fighter command, which refused to provide escorts to the U.S. Army Air Force during the daylight, citing the inability to convert fighters for long ranges. This would lead the US to study the conversion of P-51 Mustangs to that use. It would also lead to considerable tension between the US and the UK on the topic of daylight escorts.
Sarah Sundin noted Pointblank on her blog:
Today in World War II History—June 10, 1943: US & UK begin Combined Bomber Offensive against Germany; priorities for bombing targets are submarine yards, aircraft & ball bearings factories, and oil targets
