British Fleets combine in largest post - war air - sea exercises . Gibraltar ; The Western Mediterranean saw its biggest air and sea ' battles ' since the last war when the Home and Mediterranean Fleets combined to force the Straits ' Operation Two Step ' - largest post - war naval - air exercises involving battleships , carriers , destroyers , submarines and RAF squadrons. Photo shows ; The aircraft carrier ' Implacable ' entering Gibraltar harbour after the exercises . 11 March 1949