D-Day En Español General Dwight D. Eisenhower was appointed the Supreme Allied Commander of the Allied Expeditionary Force during World War II. As leader of all Allied troops in Europe, he led "Operation Overlord," the amphibious invasion of Normandy across the English Channel. Eisenhower faced uncertainty about the operation, but D-Day was a military success, though at a huge cost of military and civilian lives lost, beginning the liberation of Nazi-occupied France. Read more... Primary Sources