In December 1918 he became the leader of a scouts sabotage unit, which attacked the Soviets stationed in
Ukraine. During one of the raids, at
Koziatyn rail station, he was arrested, but managed to escape from jail. Later, during the
Polish-Soviet War, he carried out several missions behind the Soviet front line. As an 18-year-old boy, he was twice sentenced to death by the Soviets, but always escaped. In September 1920 he joined the Ukrainian Army of
Simon Petlura, serving there until 1922. After the war Niezbrzycki, who took education both in Polish and Russian, was introduced to
Józef Piłsudski, who offered him a job in the Headquarters of the Polish Army. His task was to work in Polish-Soviet border districts, simultaneously, he studied law and politics at the
Warsaw University, his main interest was the Soviet Union and its politics. Also, he promoted the Polish-Ukrainian union, seen by him as a counterbalance to Russia and its might. == Government agent ==