On D-Day, June 6, 1994, allied armies landed in Normandy on the northwestern coast of France, possibly the most critical event of World War II took place, the outcome of this event would determine the fat of Europe. If the invasion failed, the United States, being out of resources, might turn its full attention to the enemy in the pacific, Japan, leaving Britain alone, with most of its resources during the invasion. That would enable Nazi Germany to concentrate all its strength against the Soviet Union. By the time the U.S. came back Europe, Germany would rule the entire continent. Although fewer Allied ground troops went ashore on D-Day than on the first day of the earlier invasion of Sicily, the invasion of Normandy was in total, history's greatest amphibious operation, involving on the first day 5,000 ships, the largest armada ever assembled, 11,000 aircraft and approximately 154,000 British, Canadian and American soldiers, including 23,000 arriving by parachute and glider. The invasion also involved a plan on a scale the world had never seen and the secretive operations of tens of thousands of allied resistance fighters in Nazi-occupied countries of Western Europe. American General Dwight D. Eisenhower was named supreme commander for the Allies in Europe. British General, Sir Fredrick Morgan, established a combined American-British headquarters known as COSSAC, this stands for Chief of Staff to the Supreme Allied Commander. This developed a number of plans for the Allies, the most notable was the Operation Overlord, a large invasion of France across the English Channel. Eisenhower felt that COSSAC's plan was a solid operation. After reviewing the disastrous results of the hit-and-run raid in 1942 in Dieppe, planners decided that the strength of German defenses required not a number of separate assaults by relatively small units, but an immense concentration of power in a single main landing.