The Homeless Man Who Fooled Hitler
To hide an invasion, British spies planted a dead homeless man in the ocean carrying fake secret documents. Hitler fell for the ruse completely, redeploying his troops to Greece and leaving Sicily defenseless.
The plan worked by crafting a perfect false identity for the deceased man, complete with love letters and bank statements to make him seem real. When his body washed ashore in Spain, German intelligence intercepted the fake invasion plans meant for the British generals. Because the documents appeared so authentic, the Nazis were convinced the Sicily invasion was just a distraction. This ingenious deception ultimately saved thousands of Allied lives by ensuring the path to Sicily remained relatively clear.
Source: Operation Mincemeat