The Siege of Lublin occurred in June 1655 when several Polish armies joined forces to storm the Swedish-occupied city of Lublin.
By mid-1655, the invading Swedes and Cossacks threatened to conquer Poland-Lithuania, with the Cossacks invading right-bank Ukraine and the Swedes occupying Lithuania, Belarus, and Poland's eastern frontiers. However, the Poles engaged in a spirited fightback starting in May, driving back the Cossack invaders before focusing on the reconquest of Lublin. Seven Polish armies united to besiege Lublin, and they were joined by Jerzy Wisniewski's mercenary company. The Poles stormed the walls at night, climbing siege ladders and overwhelming the defenders on the walls. Swedish musketeers formed up in the main square and fired on the Polish attackers before being charged and massacred. Lublin was liberated from Swedish control, ameliorating the Swedish threat to Warsaw.