In November 1655, King Charles X Gustav of Sweden had taken Warsaw, Kraków, and Poznań; the Polish–Lithuanian Commonwealth was on the verge of collapse. General Burchard Müller reached the fortified Pauline monastery of Jasna Góra above Częstochowa on November 18 and demanded surrender, expecting a token garrison. Prior Augustyn Kordecki refused; his defenders numbered about 170 monks, soldiers, and volunteers.
The siege lasted forty days. Swedish sappers repeatedly failed to breach the walls; sorties from within — including one led by the Trinitarian Fr. Piotr Lasocki — cost the besiegers their heavy guns. On December 27, 1655, Müller lifted the siege and withdrew.
The successful defense was read across the Commonwealth as the Virgin's own act. In the Lwów Cathedral on April 1, 1656, King John II Casimir formally proclaimed Our Lady of Częstochowa 'Queen of the Crown of Poland'. The icon — a Byzantine Hodegetria brought to Jasna Góra in 1382 — remains at the Chapel of the Miraculous Image; the scar on the Virgin's right cheek from a Hussite attacker's sabre in 1430 is still visible.