From the outbreak of the Second World War, Hartnell attempted to volunteer for the RAF. He served in the British Army in the Tank Corps, but he was invalided out after 18 months as the result of a nervous breakdown and returned to acting. In 1942 he was cast as Albert Fosdike in Noël Coward's film "In Which We Serve". He turned up late for his first day of shooting, and Coward berated him in front of the cast and crew for his unprofessionalism, made him personally apologise to everyone and then sacked him. Michael Anderson, who was the first assistant director, took over the part (and was credited as "Mickey Anderson").