 At the outbreak of war in September 1939, he led this unit in the invasion of Poland, then afterward took up an administrative post for a short term, in the headquarters of Luftflotte 2.On 15 December 1939, Schellmann was appointed commander the newly formed II./Jagdgeschwader 2 (JG 2—2nd Fighter Wing).During the Battle of Britain, on 3 September he was promoted to commander of JG 2.