Warsaw falls without resistance to a small force under the command of Charles X Gustav of Sweden during The Deluge, making it the first time the city is captured by a foreign army.

Warsaw, officially the Capital City of Warsaw, is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland. Its population is officially estimated at 1.86 million residents within a greater metropolitan area of 3.27 million residents, which makes Warsaw the 6th most-populous city in the European Union. The city area measures 517 km² (200 sq mi) and comprises 18 districts, while the metropolitan area covers 6,100 km² (2,355 sq mi). Warsaw is classified as an alpha global city, a major political, economic and cultural hub, and the country's seat of government. It is also the capital of the Masovian Voivodeship.

Charles X Gustav, also Carl X Gustav, was King of Sweden from 1654 until his death. He was the son of John Casimir, Count Palatine of Zweibrücken-Kleeburg and Catherine of Sweden. After his father's death he also succeeded him as Pfalzgraf. He was married to Hedwig Eleonora of Holstein-Gottorp, who bore his son and successor, Charles XI. Charles X Gustav was the second Wittelsbach king of Sweden after the childless king Christopher of Bavaria (1441–1448) and he was the first king of the Swedish Caroline era, which had its peak during the end of the reign of his son, Charles XI. He led Sweden during the Second Northern War, enlarging the Swedish Empire. By his predecessor Christina, he was considered de facto Duke of Eyland (Öland), before ascending to the Swedish throne. From 1655 to 1657, he was also Grand Duke of Lithuania.

The Deluge was a series of mid-17th-century military campaigns in the Polish–Lithuanian Commonwealth. In a wider sense, it applies to the period between the Khmelnytsky Uprising of 1648 and the Truce of Andrusovo in 1667, comprising the Polish theatres of the Russo-Polish and Second Northern Wars. In a stricter sense, the term refers to the Swedish invasion and occupation of the Commonwealth as a theatre of the Second Northern War (1655–1660) only; in Poland and Lithuania this period is called the Swedish Deluge, or less commonly the Russo–Swedish Deluge due to the simultaneous Russo-Polish War. The term "deluge" was popularized by Henryk Sienkiewicz in his novel The Deluge (1886).