The letter contained a passage that was particularly clever. It acknowledged that the enemy might expect an attack on Sicily, calling it “an obvious objective and one about which he must be nervous,” and suggested framing Sicily as the cover story for the actual Greek operations. This meta-layer, making Sicily appear to be Allied deception rather than the actual target, had the potential to make German analysts who were already alert to Allied deception efforts think they had caught the Allies in the act of using Sicily as a false flag.
In other words, the document said, in effect: “We know the Germans expect Sicily; let’s use that against them by pretending Sicily is our cover story while we actually go for Greece.” A German intelligence reader who picked that up would feel he had seen through one layer of Allied deception only to find the real plan underneath. The real plan was, in fact, Sicily. But by the time German analysts reached this layer, they believed they had done their professional jobs well by seeing through the British misdirection.
This kind of nested deception, where the planted document appears to reveal the Allied cover story, making the cover story seem like the false layer, was exactly the sophisticated operation that Montagu had designed.
Vice-Admiral Lord Louis Mountbatten contributed a second letter, addressed to Admiral Sir Andrew Cunningham. The Mountbatten letter introduced Major Martin as an amphibious warfare expert being loaned to Cunningham’s command for the coming operations. It asked Cunningham to return Martin at the conclusion of the operation.