Although Kotor lies within Montenegro, it had a special status due to its history. Kotor had been an Austrian enclave until 1918. Kotor was an important port on the Adriatic which Italy aquired after the fall of Yugoslavia in 1941. It became an Italian enclave and used normal Italian stamps from 1941 to 1943.
After the fall of Italy in September 1943 Kotor was occupied by the Germans, however Kotor continued to use Italian stamps without overprint and also occupation issues from Montenegro. In 1944 the Germans produced a stamp issue which were Italian stamps overprinted with "Deutsche Militär Verwaltung Kotor". All three issues could be used at the same time allowing for an interesting mix on the early postal items.
All overprints were added at the printers in Cetinje, the same printers who overprinted the Montenegro issues.