Exercise OA tested mixed battle fleets and divided screens

OA began with a Gibraltar relief setting and asked how a battleship force should fight an opponent mixing battleships and battlecruisers. It also tested whether destroyer flotillas should be divided into groups on each wing of the approaching battle fleet. Cardiff, Caledon, Vindictive, and Comus fought under heavy pressure while the Third Cruiser Squadron lost its bearing on the battle fleet. Once the danger from submarines seemed to have passed, the destroyers moved into wing positions for their attack. A reported downed reconnaissance aircraft drew Argus and the First Flotilla away to rescue the aircrew and salvage the machine. Neither could rejoin before the action, showing how an essential rescue could abruptly change the force available for a planned battle.