This was a British tactical deception designed to persuade the German force holding the Halfaya Pass area to surrender (29/30 December 1941).
This German force, commanded by Major Wilhelm Bach, had been left to hold this strategic Halfaya Pass as the Axis forces retreated after the 'Crusader' (i) fighting, and the 'Gripfix' tactical ruse was designed to bring about Bach’s surrender by dropping into the German perimeter a forged letter, purportedly from General Erwin Rommel, commander of the Panzergruppe 'Afrika', authorising Bach to make an honourable surrender. The letter was prepared by skilled forgers with considerable care, written on captured German stationery, stamped with markings made with captured German rubber stamps, and sealed with a German army seal specially forged for this project. The forged letter was dropped in captured German containers on the night of 29/30 December. The stationery used was obsolete, however, and while Lieutenant Colonel Dudley W. Clarke’s 'A' Force deception organisation was aware of this, it had decided to take a chance on the feeling that a commander with supply difficulties, such as those under which Rommel was operating, would nonetheless make use of existing stocks. Even so, this raised suspicion in Bach’s mind. Moreover, on 30 December Bach received a message from Adolf Hitler himself congratulating the defenders of the Halfaya Pass and urging them to hold on as long as they could.
'Gripfix' therefore failed, and Bach did not surrender until 17 January 1942.