Ultra intercepted messages between German intelligence stations in Spain and Berlin confirmed the access more directly. The intercepts showed that Clauss had reported the contents of the documents and that the reports were being processed and acted upon. By mid-May 1943, British intelligence had documentary evidence, from German communications, that the Mincemeat documents had been received, believed, and were influencing German military planning.
The formal date of the Ultra confirmation is usually cited as May 14, 1943, when an intercept described the documents as having been believed by German intelligence. The message, in Montagu’s later account and in the declassified intelligence history, is described as indicating that the operation had been “swallowed rod, line and sinker.” This phrase — or a phrase very close to it — appears in accounts of the confirmation signal, though the exact wording varies between different sources.
The phrase itself is a conscious echo of the fishing metaphor in Fleming’s original Trout Memo. Whether it was used deliberately as a callback to that document is uncertain, but the operational community was aware of the Trout Memo’s fishing analogy, and the confirmation language reflected the same metaphor.
The body was buried in the Nuestra Señora cemetery in Huelva, under the name William Martin, with military honors appropriate to his stated rank. The British consul arranged for the burial, which was the ordinary thing to do with the body of a British officer who had died in Spanish waters. The grave was there from the spring of 1943 onward, a real grave with a real headstone, marking the resting place of a man who had never actually existed.