The Overlord movie is completely fictional. It's not rooted in any true events or real-life circumstances. It's all part of the imagination of the filmmakers and writers.
Yes, 'Overlord' is based on a true story. It's about the D - Day landings during World War II. The movie takes elements from the real - life events of the Allied forces' invasion of Normandy. It shows the chaos, heroism, and challenges that the soldiers faced during that fateful day.