Complex sentence: The Pinsk massacre was the murder of thirty-five Jewish residents of Pinsk taken as hostages by the Polish Army after it captured the city in April 1919, during the opening phases of the Polish-Soviet War.
Split into simpler sentences: The Pinsk massacre resulted in the death of thirty-five Jewish residents of Pinsk who were taken as hostages by the Polish Army. The event occurred after the Polich Army captured Pinsk in April 1919 during the opening stages of the Polish-Soviet War.