When NATO was created in 1949, it had very little in the way of a military structure.

The NATO Military Committee, composed of the Chiefs of Defence of the member nations, met infrequently and there were no supreme commanders or multinational headquarters to provide command and control of NATO forces in crisis and war.

Thus from 1949 until the spring of 1951 (when Allied Command Europe was activated under the first SACEUR, General Dwight D. Eisenhower), NATO's military structure consisted of five Regional Planning Groups with the task of drawing up plans for the defence of their areas.

The five Regional Planning Groups were Western Europe, Northern Europe, Southern Europe and the Mediterranean, the North Atlantic Ocean, and Canada-United States.