Operation Mincemeat was an elaborate deception by the British. It took place in 1943. The purpose was to convince the Nazis that Britain was going to invade Greece, when in fact, the target was Sicily.
Operation Mincemeat was an interesting story, just as a tale for a movie. But it was based on truth and actually happened. If you’re really into the history of World War II, the page for the film on IMDb has lots of interesting trivia. This includes previous films and several books that have dealt with the same events. And Wikipedia has a long account of the operation and a list of references.
There were many moving parts in this elaborate ruse. The four main characters were Ewen Montagu (Colin Firth), Charles Cholmondeley (Matthew Macfadyen), Jean Leslie (Kelly Macdonald), and Hester Leggett (Penelope Wilton).
Once the crazy idea to use a dead body to carry fake documents to the German army was hatched, it was these four who ironed out the details. They sat in bars and restaurants dreaming up details to make it all seem real, and figuring out ways to carry out the plan. The had to convince all their superiors, including Winston Churchill, that it was a good idea.
The four gave the dead man a new name, created fake documents that made it look like the invasion would be in Greece, gave him a fake girlfriend and fake love letters, and dropped him into the sea so he’d wash up on the shore in Spain. From there, they had to hope and pray that the Spanish would turn the documents over to the Germans.
The film was directed by John Madden from a screenplay by Michelle Ashford. The film was a bit stodgy. The opening seconds were dull and without promise, but things changed quickly. The screenplay included enough personal relationships and human interest to keep things moving. There were voiceovers from Ian Fleming (Johnny Flynn), who was writing a spy novel about what was happening as it happened.
You can see Operation Mincemeat on Netflix.