Rebel plans envisaged the Polish Army attacking the Russian Infantry Corps of the Tsar's Guard, which made camp between Augustów and Ostrołęka. On 18 May 1831 General Henryk Dembiński claimed Ostrołęka. But General Jan Zygmunt Skrzynecki didn't make a use of his temporary superiority and he couldn't make up his mind whether to attack the Russians situated near Łomża. As a result, Łomża was destroyed. thumb|left|Battle of Ostrołęka (1831) On 26 May 1831 the Battle of Ostrołęka (1831) took place. 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 Bernardine Monastery. Unfortunately the Russians had brought cannons with them; they quickly overpowered the Polish units and forced their surrender.
Rebel plans envisaged the Polish Army attacking the Russian Infantry Corps of the Tsar's Guard, which made camp between Augustów and Ostrołęka. On 18 May 1831 General Henryk Dembiński claimed Ostrołęka. But General Jan Zygmunt Skrzynecki didn't make a use of his temporary superiority and he couldn't make up his mind whether to attack the Russians situated near Łomża. As a result, Łomża was destroyed. thumb|left|Battle of Ostro?łęka (1831) On 26 May 1831 the Battle of Ostrołęka (1831) took place. 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 Bernardine Monastery. Unfortunately the Russians had brought cannons with them; they quickly overpowered the Polish units and ,forced their surrender.