The 24 cm Kanone M. 16 was a super-heavy siege gun used by Austria-Hungary during World War I and by Nazi Germany during World War II. Only two were finished during World War I, but the other six were completed in the early twenties and served with the Czechoslovak Army until they were bought by the Germans after their Munich Agreement in 1938. During World War I one gun served on the Western Front and the other on the Italian Front. During World War II they saw action in the Battle of France, Operation Barbarossa and the Siege of Leningrad.