This was a British deception designed to create disaffection and reduce morale in the 8th Panzerregiment in the Western Desert (April 1942).
The undertaking provided for the delivery into German hands of a forged letter purporting to come from a previous commander, who was against the Nazis and had been transferred back to Germany, to the current commander, Oberstleutnant Willi Teege.
The regiment was a key component of Generalmajor Gustav von Vaerst’s 15th Panzerdivision, and this 'dirty' trick' effort, which was the only such effort by Colonel Dudley W. Clarke’s 'A' Force Middle Eastern deception apparatus, was designed to degrade its capability. 'H.D.F.', as the operation was generally known, was intended to sow suspicion that Teege was involved in an anti-Hitler plot. The 'A' Force forger prepared a letter purportedly emanating from the colonel in Germany to his successor, saying that he had seen two senior generals, who had told him that 'the move they had often discussed' was progressing well, and that they had asked him to dissuade his officers from any premature step which might jeopardise the matter. It even went as far as to hint that Generaloberst Erwin Rommel, commander of the Panzerarmee 'Afrika', had hinted that he might join the conspiracy.
With a cover letter purportedly smuggled out by a German prisoner, this was mailed in Istanbul to a known German agent, and there is no way to confirm the result, if any.