In this West Prussian area, a plebiscite was required to determine whether it should be German or Polish. An inter-allied commission supervised the plebscite and arranged stamps to be issued. On 11 July 1920, it was voted overwhelmingly to be attached to Germany. German stamps were re-introduced and used until after World War II, when the area was occupied by Soviet forces. Finally, it returned to Poland and was given back the name Kwidzyn.