On 1 September 1863, twelve days after his sixteenth birthday, Prus took part in a battle against Russian forces at a village called Białka, four kilometers south of Siedlce.
La 1 septembrie 1863, la douăsprezece zile după cea de-a 16-a aniversare, Prus a luat parte la o lupta împotriva rușilor, într-un sat numit Bialka, la patru kilometri la sud de Siedlce.