Following the reconquest of Greece by the Allies, German forces stationed on Crete and the Aegean Islands could only be supplied by air.
The army’s field postmaster (Feldpostmeister) for these regions, Dr. E. Schwarz of Army Group F, decreed that only mail with Feldpost stamps overprinted “Inselpost” should be transported. To accommodate this requirement, 200,000 package stamps (MiNr. 2 B) were overprinted in Vukovar, Croatia, for distribution to the troops.
However, the aircraft transporting the stock of stamps was shot down during a supply flight in October 1944. The only copies of the Vukovar printing which survived were a small stock of approximately 2,000 stamps which remained in Vukovar. These were transported to Rhodes in December 1944, where they were distributed to collectors.
During the printing process, two freshly printed sheets were placed face-to-face, resulting in transfer from one to the other and creating the double overprint with one inverted and mirror-imaged (unlisted in Michel).