Operation Mincemeat was the most famous part of the deception plan to support the invasion of Sicily, and saw the British drop the body of a vagrant dressed in naval uniform into the sea off the coast of Spain, in the hope that the Spanish would pass on the ‘confidential’ documents in his possession to the Germans.
Sicily was the next Allied target after the end of the campaign in Tunisia. The seizure of the island would secure the sea routes through the Mediterranean, and give the Allies good air fields to attack mainland Italy. However it was also the obvious next target, and so a deception plan was put in place to try and convince the Germans that the real Allied target was Greece, with diversionary attacks into Sardinia and Corsica (Operation Barclay).
The idea for Operation Mincemeat originated with Flt Lt Cholmondeley, the secretary to the Twenty Committee in London. The original plan had been to try and see how the Germans would run a compromised agent by dropping a dead body by parachute into France, complete with radio and code book. The hope was that the Germans would find the body and attempt to use that radio to run a counter-intelligence operation. However the big flaw with the idea was that it would be obvious that the body had been dead before the parachute drop.
Cholmondeley then suggested a modification of the plan. This time the body would be dumped at sea somewhere off the coast of Spain or France, in uniform, and carrying confidential papers relating to upcoming operations. As long as it looked like the victim had drowned, they would appear to be a courier whose aircraft had come down on the route from England to Africa. It was already known that the Spanish passed on any documents they found to the Germans.
A suitable body was suggested by Bentley Purchase, a coroner. This was Glyndwer Michael, a homeless Welshman, who died after drinking phosphorous rat poison. His symptoms were close enough to those of drowning not to raise suspicion in Spain. He was given a new identity as ‘Major William Martin’, matching a number of possible ‘W Martin’s on the Naval List. He was given a ‘love interest’, and a collection of private letters, receipts and theatre tickets to establish him as a real person.
The most important part of the plan were the fake documents. Martin was given two - one from General Sir Archibald Nye, Vice Chief of the Imperial General Staff to General Alexander, and one from Lord Louis Mountbatten to Admiral Sir Andrew Cunningham.
Nye’s letter discussed sending reinforcements to bolster the forces about to invade Greece, and said that an invasion of Sicily had been considered as the cover plan for this operation, but couldn’t be used as it was already being used as the cover for Operation Brimstone. The invasion of Greece was given the code name ‘Husky’, in the hope that anything the Germans would believe that anything they learnt about the real Husky actually referred to Greece. There were no other clues to the location of Brimstone in this first letter.
Mountbatten’s letter called Martin an expert in tank landing craft, and explained that he had been sent to Africa to sort out some problems there. He was to be sent back as soon as the otherwise unspecified operation was over, and was to bring back a tin of sardines, as they were rationed in England, a hint that Sardinia was the target.
The two letters were approved on 13 April. ‘Major Martin’ was then loaded onto the submarine HMS Seraph, and on 30 April he was set adrift at sea. As expected, he was soon found by a Spanish fisherman, and handed over to the Spanish army. The documents were found and copies sent to Germany. A Spanish doctor concluded that he had drowned. News of the discovery of the body was then passed on to the British Naval Attaché, who was ordered to make a fuss about the missing documents. They were returned to the British on 13 May, and it was clear that they had indeed been opened.
The operation appears to have been a success. The Germans were already expecting a British operation in the Dodecanese or Greece, so the documents supported their existing ideas. On 12 May they made the defence of Sardinia and the Peloponnese the top priority in the Mediterranean, and on 14 May Bletchley Park decoded a message indicating that the Germans believed they had ‘absolutely reliable’ information that the Allies were going to land in the western and eastern Mediterranean. Probably as a result the 1st Panzer Division was moved from France to Greece and even after the invasion of Sicily, the Germans were still convinced that Greece would be the next target.