This was a British naval training exercise in the Atlantic Ocean, using the fleet carriers Eagle, Indomitable and Victorious, to hone their crews’ fighter direction and multi-carrier operating techniques in preparation for the ‘Pedestal’ and related undertakings (5/9 August 1942).
While 'Pedestal' also involved the old carriers Argus and Furious, the more modern carriers which were to join Force 'Z' for 'Pedestal' were under the command of Rear Admiral A. L. St G. Lyster, flying his flag in Victorious. These carriers had been supplied from a number of sources. Victorious had been on the strength of the Home fleet but had departed Scapa Flow in the Orkney islands group on 31 July to join Argus from the Clyde and screened by the light anti-aircraft cruiser Sirius and six destroyers; Indomitable, covered by the light anti-aircraft cruiser Phoebe and three destroyers, had arrived from Freetown, Sierra Leone, on diversion from the Indian Ocean; and Eagle and three destroyers arrived at the Atlantic rendezvous from Force 'H' at Gibraltar.
On 5 August, well out in the Atlantic to the west of Gibraltar, Lyster gathered his three main carriers and their supporting light anti-aircraft cruisers (Eagle was now complemented by Charybdis). Each of the carriers also had an anti-submarine destroyer detachment. Argus was also present as the fighter director, and in support was a refuelling force from Freetown, this comprising the oiler Abbeydale escorted by the corvettes Armeria and Burdock.
Lyster now pushed his force through an intensive tactical exercise programme intended to stretch both the ships and their 72 fighters, many of them flown by pilots with only the most limted combat experience. The programme also involved the air and anti-submarine guards, which had to follow the carriers as they headed into the wind to fly off or land their aircraft, constantly changing course and speed as they worked their squadrons.
Victorious had the greatest proportion of Fairey Fulmar two-seat fighters, which were tasked with low-altitude air cover, while Eagle and Indomitable had a higher proportion of Grumman Wildcat (known to the British as Martlet) and Hawker Sea Hurricane single-seat fighters, which were tasked with the provision of higher-altitude cover for the convoy’s merchant vessels and warships.
The exercises of 'Berserk' proved to be invaluable, and helped to raise the capabilities of the carriers' air groups to a marked degree, They also aided the development of the British fighter-direction techniques.