 In early 1943, an underground Jewish resistance organisation was formed at Treblinka with the goal of seizing control of the camp and escaping to freedom. The planned revolt was preceded by a long period of secret preparations. The clandestine unit was first organised by a former Jewish captain of the Polish Army, Dr. Julian Chorążycki, who was described by fellow plotter Samuel Rajzman as noble and essential to the action. His organising committee included Zelomir Bloch (leadership), Rudolf Masaryk, Marceli Galewski, Samuel Rajzman, Dr. Irena Lewkowska ("Irka", from the sick bay for the Hiwis), Leon Haberman, Hershl (Henry) Sperling from Częstochowa, and several others. Chorążycki (who treated the German patients) killed himself with poison on 19 April 1943 when faced with imminent capture, so that the Germans could not discover the plot by torturing him. The next leader was another former Polish Army officer, Dr. Berek Lajcher, who arrived on 1 May. Born in Częstochowa, he had practised medicine in Wyszków and was expelled by the Nazis to Wegrów in 1939.
