It was formed primarily of former officers of the Polish Army in late 1939, soon after the start of the German occupation of Poland.
The Żydowska Organizacja Bojowa (ŻOB), Polish for the Jewish Combat Organization; called in Yiddish יידישע קאמף ארגאניזאציע) - a World War II resistance movement, which was instrumental in engineering the Warsaw Ghetto Uprising (although the ŻZW Jewish resistance organization claimed otherwise).