The Siege of Jasna Gora (in Polish: Oblężenie Jasnej Góry) took place in the winter of 1655 during the Second Northern War, or ‘The Deluge’ – as the Swedish invasion of the Polish–Lithuanian Commonwealth is known. The Swedes were attempting to capture the Jasna Gora monastery in Czestochowa. Their month-long siege, however, was unsuccessful, as a small force consisting of monks from the Jasna Gora monastery led by their Prior (Fr. Augustyn Kordecki) and supported by local volunteers, mostly from the szlachta (Polish nobility), fought off the numerically superior Germans (who were hired by Sweden), saved their sacred icon, the Black Madonna of Czestochowa, and, according to some accounts, turned the course of the war.
(Wikipedia: https://en.wikipedia.org/wiki/Siege_of_Jasna_Góra )