In September 1941 Lamb's aircraft was wrecked while landing a secret agent in French North Africa and he was held by the Vichy French government at the Laghouat prison camp for a year, until freed by the Allied Allied invasion of Algeria in November 1942. After treatment for malnutrition, he spent a year recruiting flying cadets for the Fleet Air Arm, until passed fit for flying in December 1943, and joined the aircraft carrier HMS "Implacable" as Lieutenant-Commander (Flying), with an acting rank of lieutenant-commander. Aboard as Lieutenant-Commander (Flying) from May 1944, he escorted Arctic convoys and launched air strikes against the German battleship "Tirpitz". He served in "Implacable" again as Lieutenant-Commander (Flying) from 8 January 1945 until July 1945; after a catastrophic flight deck injury (struck by a broken aircraft propeller) he was hospitalized for two years before returning to naval duty.