 He was involved in the diplomatic subterfuge preceding the invasion of Denmark in 1940, and carried instructions to the embassy, together with a general's uniform for Kurt Himer, in his diplomatic bag to Copenhagen on 9 April 1940, the day of the invasion.The information Schlitter delivered equipped Himer and the embassy staffs in Copenhagen and Oslo to know what was going on.Within the service he was promoted from the rank of to that of in April 1942.