On a related note, Eisenhower prepared a statement against the possibility that the D-Day landings failed, taking full responsibility for the repulse (see: https://www.archives.gov/education/lessons/d-day-message/images/failure-message.gif Note how he edited it to strengthen the wording)

"Our landings in the Cherbourg-Havre area have failed to gain a satisfactory foothold and I have withdrawn the troops. My decision to attack at this time and place was based upon the best information available. The troops, the air and the Navy did all that Bravery and devotion to duty could do. If any blame or fault attaches to the attempt it is mine alone."

This quesiton came up about a year ago. There were some interesting answers in that thread, including this one: https://www.reddit.com/r/AskHistorians/comments/2em57g/what_was_the_back_up_plan_if_dday_failed/ck131m0