|Part of the Western Front of World War II|
LCT with barrage balloons afloat, unloading supplies on Omaha for the break-out from Normandy
|Date||6 June – 30 August 1944
(2 months, 3 weeks and 3 days)
Italian Social Republic[a]
|Commanders and leaders|
- 1,452,000 troops (by 25 July)[b]
- 2,052,299 (by the end of August)
- 380,000 troops (by 23 July)
- ~640,000 troops total
- 2,200 – 2,500 tanks and assault guns
|Casualties and losses|
- 288,695 to 530,000 casualties
- 2,127 aircraft
- 1,500 to 2,400 tanks and assault guns lost
- 11,000–19,000 killed in pre-invasion bombing
- 13,632–19,890 killed during invasion
- Total: 25,000–39,000 killed
Operation Overlord was the codename for the Battle of Normandy, the Allied operation that launched the successful invasion of German-occupied Western Europe during World War II. The operation was launched on 6 June 1944 with the Normandy landings. A 1,200-plane airborne assault preceded an amphibious assault involving more than 5,000 vessels. Nearly 160,000 troops crossed the English Channel on 6 June, and more than two million Allied troops were in France by the end of August.
The decision to undertake a cross-channel invasion in 1944 was taken at the Trident Conference in Washington in May 1943. General Dwight D. Eisenhower was appointed commander of Supreme Headquarters Allied Expeditionary Force, and General Bernard Montgomery was named as commander of the 21st Army Group, which comprised all the land forces involved in the invasion. The coast of Normandy of northwestern France was chosen as the site of the invasion, with the Americans assigned to land at sectors codenamed Utah and Omaha, the British at Sword and Gold, and the Canadians at Juno. To meet the conditions expected on the Normandy beachhead, special technology was developed, including two artificial ports called Mulberry harbours and an array of specialised tanks nicknamed Hobart's Funnies. In the months leading up to the invasion, the Allies conducted Operation Bodyguard, a substantial military deception that used electronic and visual misinformation to mislead the Germans as to the date and location of the main Allied landings. Führer Adolf Hitler placed German Field Marshal Erwin Rommel in charge of developing fortifications all along Hitler's proclaimed Atlantic Wall in anticipation of an invasion.
The Allies failed to accomplish their objectives for the first day, but gained a tenuous foothold that they gradually expanded when they captured the port at Cherbourg on 26 June and the city of Caen on 21 July. A failed counterattack by German forces on 8 August left 50,000 soldiers of the 7th Army trapped in the Falaise pocket. The Allies launched a second invasion from the Mediterranean Sea of southern France (code-named Operation Dragoon) on 15 August, and the Liberation of Paris followed on 25 August. German forces retreated east across the Seine on 30 August 1944, marking the close of Operation Overlord.
Preparations for D-Day
In June 1940, Germany's leader Adolf Hitler had triumphed in what he called "the most famous victory in history"—the fall of France. British craft evacuated to England over 338,000 Allied troops trapped along the northern coast of France (including much of the British Expeditionary Force (BEF)) in the Dunkirk evacuation (27 May to 4 June). British planners reported to Prime Minister Winston Churchill on 4 October that even with the help of other Commonwealth countries and the United States, it would not be possible to regain a foothold in continental Europe in the near future. After the Axis invaded the Soviet Union in June 1941, Soviet leader Joseph Stalin began pressing for a second front in Western Europe. Churchill declined because he felt that even with American help the British did not have adequate forces for such a strike, and he wished to avoid costly frontal assaults such as those that had occurred at the Somme and Passchendaele in World War I. Two tentative plans code-named Operation Roundup and Operation Sledgehammer were put forward for 1942–43, but neither was deemed by the British to be practical or likely to succeed. Instead, the Allies expanded their activity in the Mediterranean, launching the invasion of French North Africa in November 1942, the invasion of Sicily in July 1943, and invading Italy in September. These campaigns provided the troops with valuable experience in amphibious warfare.
Attendees at the Trident Conference in Washington in May 1943 took the decision to launch a cross-Channel invasion within the next year. Churchill favoured making the main Allied thrust into Germany from the Mediterranean theatre, but the Americans, who were providing the bulk of the men and equipment, over-ruled him. British Lieutenant-General Frederick E. Morgan was appointed Chief of Staff, Supreme Allied Commander (COSSAC), to begin detailed planning. The initial plans were constrained by the number of available landing-craft, most of which were already committed in the Mediterranean and in the Pacific. In part because of lessons learned in the Dieppe Raid of 19 August 1942, the Allies decided not to directly assault a heavily defended French seaport in their first landing. The failure at Dieppe also highlighted the need for adequate artillery and air support, particularly close air support, and specialised ships able to travel extremely close to shore. The short operating-range of British aircraft such as the Spitfire and Typhoon greatly limited the number of potential landing-sites, as comprehensive air-support depended upon having planes overhead for as long as possible. Morgan considered four sites for the landings: Brittany, the Cotentin Peninsula, Normandy, and the Pas de Calais. As Brittany and Cotentin are peninsulas, the Germans could have cut off the Allied advance at a relatively narrow isthmus, so these sites were rejected.
Pas de Calais