Colonel Berek Joselewicz wearing of Duchy of Warsaw mounted riflemens uniforms.

Berek Joselewicz (c.1764–1809) was a Jewish merchant and military officer who raised and commanded a Jewish cavalry regiment in support of Tadeusz Kościuszko's 1794 uprising — the first time Jews were recruited into a Polish fighting force as a distinct unit. His death at the Battle of Kock in 1809 fighting under Napoleonic colours ensured his place in the pantheon of Polish-Jewish patriotic heroes. Kossak's 1850 depiction places Joselewicz in the uniform of the Duchy of Warsaw's mounted riflemen, showing the later stage of his military career under Napoleon rather than the 1794 uprising. In nineteenth-century partitioned Poland, Joselewicz was a potent symbol of Jewish participation in the struggle for Polish independence — a figure invoked to argue that Polish and Jewish fates were intertwined. Kossak's equestrian treatment gives Joselewicz full heroic stature: he is not a footnote but a central figure in the national story, rendered with the same care the painter brought to Poniatowski or Dąbrowski.

The equestrian format is the natural vehicle for Kossak's celebration of military heroes: horse and rider are presented as a unified emblem of martial virtue. The Duchy of Warsaw mounted rifleman's uniform is painted with documentary precision. The horse's controlled energy under its rider is a recurring Kossak motif — power disciplined by command.