Between 20th January and 10th May of 1942, the Partisans took over Foča and the surrounding area. They proclaimed the so-called Republic of Foča.
Among other things, the postal service was restored. They had some amount of old Yugoslav stamps on which the Ustasha overprinted its coat of arms and the inscription "NEZAVISNA DRŽAVA HRVATSKA" (= "INDEPENDENT STATE OF CROATIA"). These stamps have been used together with a five-pointed star rubber stamp and the inscription "SMRT FAŠIZMU - SLOBODA NARODU" (= "DEATH TO FASCISM - FREEDOM TO THE PEOPLE") and "Partizanska POŠTA" (= "Partisan POST").
An interesting snippet from Vladimir Dedijer's diary with two glued stamps (Mi. 12 and 41), cancelled with Foča 1.V.42 and provisional rubber stamps.
1942 Foča, Partisan provisional issue, NDH stationery with Mi. 12, overprinted with provisional rubber stamps.
1942 Foča, Partisan provisional issue, NDH stationery with Mi. P1, overprinted with provisional rubber stamps.
Comparison of rubber stamps on the stationery and in the Dedijer's diary.
For more see: Südost-Philatelie 88/2004 - Die Partisanenpost von Foca (Dr. Hermann Dietz)
