During the November Uprising, the fortress was one of main centers of Polish resistance. Commanded by Julian Sierawski and later Jan Krysinski, its garrison consisted of 3800 soldiers. Zamość was a base of Polish units operating in the area of Lublin, however, after Polish defeat in the Battle of Ostrołęka, the Russians took the initiative. The blockade of Zamość began in July 1831, and the fortress itself capitulated on November 21, as the last resistance point of the country.