Here's something interesting I came across recently. Operation Mincemeat is a 2021 film on Netflix based on a true story of espionage. From the Wikipedia article:
Operation Mincemeat was a successful British deception operation of the Second World War to disguise the 1943 Allied invasion of Sicily. Two members of British intelligence obtained the body of Glyndwr Michael, a tramp who died from eating rat poison, dressed him as an officer of the Royal Marines and placed personal items on him identifying him as the fictitious Captain (Acting Major) William Martin. Correspondence between two British generals which suggested that the Allies planned to invade Greece and Sardinia, with Sicily as merely the target of a feint, was also placed on the body.
Part of the wider Operation Barclay, Mincemeat was based on the 1939 Trout memo, written by Rear Admiral John Godfrey, the Director of the Naval Intelligence Division, and his personal assistant, Lieutenant Commander Ian Fleming. With the approval of the British Prime Minister, Winston Churchill, and the military commander in the Mediterranean, General Dwight D. Eisenhower, the plan began by transporting the body to the southern coast of Spain by submarine and releasing it close to shore, where it was picked up the following morning by a Spanish fisherman. The nominally neutral Spanish government shared copies of the documents with the Abwehr, the German military intelligence organisation, before returning the originals to the British. Forensic examination showed they had been read and Ultra decrypts of German messages showed that the Germans fell for the ruse. German reinforcements were shifted to Greece and Sardinia before and during the invasion of Sicily; Sicily received none.
The full effect of Operation Mincemeat is not known, but Sicily was liberated more quickly than anticipated and losses were lower than predicted. The events were depicted in Operation Heartbreak, a 1950 novel by the former cabinet minister Duff Cooper, before one of the intelligence officers who planned and carried out Mincemeat, Ewen Montagu, wrote a history in 1953. Montagu's work formed the basis for the 1956 British film The Man Who Never Was. A second British film based on the events was released in 2022 under the title Operation Mincemeat.
What a yarn.