This was an Allied tactical deception plan in support of 'Husky' (i) (July 1943).
The plan’s object was to contain the German and Italian forces in the western part of the island of Sicily for as long a time as possible, as certainly for three days after the 'Husky' (i) landings on the south-eastern corner of the island, and this was achieved to a significant degree with the aid of other deceptions including 'Fanfare' (i).
'Derrick' was based on the threat of an amphibious assault on Marsala, at the western extremity of the island, on 12 July by a fake invasion force launched from Bône on the north coast of Tunisia. It had been planned that as many as 100 dummy landing craft would be concentrated in this port to add verisimilitude to 'Derrick', but in the event only 12 could be made available, and their realism was sadly degraded by the fact that they were blown about by the wind. Troops in northern Tunisia also acted a part in simulated preparations for embarkation, and follow-on convoys for 'Husky' (i) departed North Africa on 11 July on courses that would take them to Marsala, changing course to their real destinations only after the fall of darkness. Other elements of the plan were simulated preparation of assault beaches by beach jumpers, and the dropping of exploding dummy parachutists in the area close behind the national assault beaches.
The execution of 'Derrick' was beset by a number of failures, but was nonetheless successful to a marked degree. As late as three days after the launch of 'Husky' (i), Italian commanders on western Sicily believed that the main Allied assault would fall on their area, and Generalmajor Paul Conrath’s Panzerdivision 'Hermann Göring', one of the only two German divisions on the island, was still retained in the area two days after the start of 'Husky' (i).