According to "Bitter Glory" by Richard M Watt and other books the Polish army seized power in a coup in 1926 and the country remained a military dictatorship until it was overrun by the Germans and Russians in 1939. Note in Pre WW II Poland there were large numbers of Jews, germans, Belorussians, and Ukarinians living in Poland who were treated like second class citizens by the Poles. The Post WW II Polish state was mostly all Polish.