After a spell as an instructor in the UK, Plagis returned to action in September 1943 as commander of No. 64 Squadron, flying Spitfire Mk VCs over northern France. He took command of No. 126 (Persian Gulf) Squadron in June 1944, and led many attacks on German positions during the invasion of France and the campaign that followed; he was shot down over Arnhem during Operation "Market Garden", but only lightly wounded. After converting to Mustang IIIs, he commanded a wing based at RAF Bentwaters that supported bombing missions. He finished the war with the rank of squadron leader and remained with the RAF afterwards, operating Gloster Meteors at the head of No. 266 (Rhodesia) Squadron.