In January 1922, Hvass became a secretary if the
Ministry of Foreign Affairs. He served as minister secretary from 1925 to 1927 and was then appointed as vice consul in
Hamburg. In 1930–33, he returned to the job as minister secretary. He then worked at the
Danish embassy in
London from 1933 to 1936. He then worked in the Ministry of Foreign Affairs for 12 years, from 1941 to 1945 as head of the political-legal department and in 1945–48 as director. In 1949, with title of Major-General, he was appointed as head of the Danish military mission in
Berlin and the diplomatic mission in
Rome. He served as Danish ambassador to
Bonn in 1951–66. ==World War II==