He was captured during the Soviet invasion of Poland, but escaped and joined one of the first Polish resistance organizations, the Związek Walki Zbrojnej, which later became the Armia Krajowa.

[2] At the beginning of 1947, he took part in actions against the law enforcement agencies and the military of the communist authorities, particularly the milicja, and the functionaries of the Urząd Bezpieczeństwa and their informers.

Later in 1947 he joined a unit led by a Wolność i Niezawisłość officer, Zdzisław Broński (nom de guerre "Uskok"), which operated northeast of Lublin.

[2] In 1948, during a botched bank robbery, his cadre was intercepted by government forces and destroyed; from that time Franczak worked alone, as more and more of his former colleagues were killed, arrested, or simply gave up – especially after the amnesty of April 27, 1956.

The Lublin field office of the Polish secret police, the Służba Bezpieczeństwa, had already begun a plan to capture or kill him as early as November 1951, under the codename "Pożar" ("Fire").

On 21 October 1963, 35 functionaries of a ZOMO (paramilitary riot police) unit surrounded a barn in Majdan Kozic Górnych, the village where Franczak was in hiding.

They demanded his surrender; Franczak presented himself as a local peasant, but after having been asked about identity documents, he opened fire and was mortally wounded in the ensuing firefight.

The Institute also organized a conference about Franczak and anti-communist resistance movements, and the local TV station Telewizja Lublin made a film dedicated to him.