Invasion of Normandy, also known as D-Day or Operation Overlord, was a cross channel attack planned by the allies that took place over the English channel. Not only was D-Day the largest amphibious assault the world had seen, it was a critical point in World War II. (Locke, Alain, ed. Pg 203)The Invasion of Normandy is when the allies decided that they must take an offense and invade Germany on their home land if Hitler was to be stopped. The allies put all of their power together, for failure was not an option. If the invasion was to fail it was quite likely that the United States would have to postpone their fight against Germany and turn their full attention to the war in the Pacific, leaving the fate of Europe to Britain and the Soviet Union. Chances are that by the time the United states returned to fight Germany, Hitler would have overrun the continent since all of Britain's resources had been drained, leaving the majority of the fighting to the Soviet Union. Towards the end of November 1943, President Roosevelt, Churchill and Stalin met in Tehran for the first meeting about how to invade Germany. Roosevelt and the prime minister had already agreed that it would be best to launch a cross-channel attack, code named Overlord. President Roosevelt was in full favor of launching operation Overlord as soon as the weather permitted. With Stalin's agreement to join in, operation Overlord was set for May 1944, depending on the weather. (Anderson, Jervis. Pg 86) American General Dwight D. Eisenhower was named supreme commander for the allies in Europe. British General, Sir Frederick Morgan, established a combined American-British headquarters known as COSSAC, for Chief of Staff to the Supreme Allied Commander. COSSAC came up with a number of plans for the Allies, including Operation Overlord. Eisenhower felt that operation Overlord was a sound plan in general, but needed a few revisions. After the disastrous hit-and-run raid i...