Did deception and secretiveness play a decisive role in World War II from 1943 on?

Question

Did deception and secretiveness play a decisive role in World War II from 1943 on? Please note two aspects of my question. First, “deception and secretiveness” is broader than formal strategic tricks or plots (although the phrase can include them) and might also mean information deliberately withheld even from allies. Second, “decisive” asks you to judge not only whether such strategies happened, but also whether you think they make a difference in the outcome of the war. 500 words or more

Answer 1

 

One illustrative fact: Gen. Patton's appointment to command a fake invasion force operating from England, where fake tanks were built to fool aerial reconnaisance.