After the Soviet invasion of Poland in 1939 , despite having retired , he was arrested together with thousands of other Polish military personnel . He was held in Starobielsk . In April 1940 , the month of his seventy-fourth birthday , he would become one of the victims of the Katyn massacre of Polish prisoners of war . Among the Katyn victims were 14 Polish generals including Leon Billewicz , Bronisław Bohatyrewicz , Xawery Czernicki ( admiral ) , Stanisław Haller , Aleksander Kowalewski , Henryk Minkiewicz , Kazimierz Orlik-Łukoski , Konstanty Plisowski , Rudolf Prich ( murdered in Lviv ) , Franciszek Sikorski , Alojzy Wir-Konas , Piotr Skuratowicz , and Mieczysław Smorawiński
Katyn massacre
Katyn massacre
Leonard Skierski