The challenges facing General Dwight Eisenhower before the Invasion of Normandy were not merely military but political as well. He knew that to liberate France, and to hold it, the Allies needed local help, which would necessitate coordinating with the highly independent French resistance groups known collectively as the maquis. The Allies' objective was to push the Germans out of France. The French objective, on the other hand, was a France free of all foreign armies, including the Allies. President Roosevelt refused to give full support to Charles de Gaulle, whom he mistrusted, and declined...