The 'Partizaner-Marsh' (March of the Partisans) was written by Shmerke Kaczerginski in the summer of 1943, when the Vilna partisans withdrew to the forests surrounding the ghetto. He based his text on Hanns Eisler and Bertolt Brecht's 1934 song 'Einheitsfrontlied' (Song of the United Front), which was a popular anthem of the communist and socialist movements. Making reference to the Vilna ghetto's underground Fareynigte Partizaner Organizatsye (United Partisans’ Organisation, FPO), the chorus resounds: 'Hey, FPO! We are here! In battle, courageous and bold'.