Late on June 5, 1944, after days of tense weather delays, General Dwight D. Eisenhower gave the order 'OK, let's go' to launch Operation Overlord. Within hours, more than 13,000 American, British, and Canadian paratroopers boarded aircraft and gliders bound for Normandy, spearheading the largest amphibious invasion in history, which would unfold on the beaches at dawn on June 6.
Eisenhower had delayed the invasion by 24 hours because of storms in the English Channel, and his meteorologist, Group Captain James Stagg, identified only a brief window of marginally acceptable weather for June 6. Eisenhower weighed the decision alone in a trailer near Portsmouth, aware that postponing further risked losing the tidal and lunar conditions needed for weeks, and that troops already loaded onto ships could not be held in readiness indefinitely without compromising secrecy.
Before giving the final go-ahead, he visited paratroopers of the 101st Airborne Division at Greenham Common, chatting with blackened-face soldiers loaded with equipment, some of whom he privately believed might suffer 80 percent casualties in the night drop. He wrote a note taking full personal responsibility in case of failure, tucking it into his wallet in case the invasion collapsed.
The paratroopers who lifted off that night into darkness and flak became the first Allied soldiers to fight on French soil since 1940, tasked with securing bridges and causeways inland of the beaches before the seaborne assault began at first light.