Aerial photograph of the D-Day landings
1-Planning for D-Day began in in 1943 with Dwight D Eisenhower made supreme commander. The British general Bernard Montgomery, was put in charge of the land troops. The American and British generals jointly developed the plans for the invasion of western Europe. The invasion was known by its codename Operation Overlord. The public did not know that the Allies were planning an invasion but it was widely believed that they were.