Exercise Fabius was a formal exercise for the Allied Operation Neptune in World War II. (The other was Exercise Tiger, which had occurred a week earlier.)
The exercise was planned to start on 2 May 1944, but bad weather delayed it to the next day. It consisted of six separate exercises:
They formed the largest amphibious training exercise of the war. As the final exercise before Operation Neptune, it resembled closely the final operation and no major changes could be made to Operation Neptune.