The Casablanca Conference had resolved that Northern Europe would be invaded by the Allies in the Spring of 1944. Hopes that it might be possible to move sooner had evaporated following detailed studies about how many troops and how much shipping would be needed. It was still thought there might be a chance of moving sooner if there were signs of a collapse in the Nazi regime.
Now the Combined Chiefs of Staff of America and Britain moved to establish much more concrete plans. There was much left to consider, not least who the Supreme Allied Commander would be. Even without a Commander it was decided to appoint a Chief of Staff. For the moment what would become ‘Operation Overlord’ went without a codename. General Frederic Morgan received these orders:
12th April 1943
The CCS have decided to undertake preparations for operations against Europe;
The object is to defeat German fighting forces in Northwest Europe;
The CCS have decided to appoint a Supreme Allied Commander (SAC) in the future;
They have decided to appoint you Chief of Staff to the Supreme Allied Commander (COSSAC) pending SAC’s appointment;
You will prepare plans in the following order of priority:
1. For a return to the Continent with such forces as are available in the event of a German collapse, weakening, or withdrawal. i.e. Operation RANKIN.
2. For a limited cross-channel assault with a target date of 1 August 1943, to seize and hold a bridgehead such as the Cotentin Peninsula, in case the CCS decide at a later date to execute such an operation.
3. For a full-scale invasion of northwest Europe in the Spring of 1944.
Small-scale amphibious operations (COMMANDO raids) will be dealt with by the Chief of Combined Operations consulting you;
You will be provided with monthly forecasts of forces likely to be available for RANKIN and other operations;
When you have completed your plans you will report to the CCS.
You will be provided with a staff drawn from the British and U.S. Navies, Armies, and Air Forces.
Service Ministries and ETOUSA will assist on administration and logistic aspects of your plans.
Controlling Security Officer will be consulted for coordination of cover plans and deception.