On 26 May 1831, occurred the Battle of Ostrołęka (1831). As a cannonade was heard, Jan Zygmunt Skrzynecki couldn't believe that Hans Karl von Diebitsch (a Russian general) had already reached the suburbs of the city. He ordered the Fourth Infantry Regiment to defend the city. The main defending forces fortified themselves in the Bernadine Monastery. Unfortunately the Russians had brought cannons with them, quickly overpowering the Polish and forcing their surrender.