Normandy’s success was entirely dependent upon Patton’s deception of an invasion at Pas de Calais.
While I’m huge fan of Patton, the success of those who actually landed was largely due to the actual fighting they did, and the offshore and aerial support.
There was lots of deception involved to try to tie down the Germans at Calais, including Double Cross, and the real ace up the Allies’ sleeve was that Hitler was a dumbass, or more specifically, he didn’t grasp either strategy or tactics.
The Higgins boats, LSTs, and Mulberry harbo(u)rs, and unprecedented airlift capability, and thee overall industrial output of the US, all contributed to the success.
For his part, Patton achieved more with less than most (or all?) commanders in the war in any participating armed forces. And he pissed in the Rhine, March 24, 1945 at Oppenheim, as he crossed over a pontoon bridge and into Germany, and [snip] sent a dispatch to Allied Supreme Commander Gen. Dwight D. Eisenhower that read, “I have just pissed into the Rhine River. For God’s sake, send some gasoline.” [/snip] The bridge had been put in place on the 22nd, and a division of his Third Army had already crossed over.
https://www.skillsetmag.com/general-patton-at-the-rhine/