Michael I (Polish: Michał Korybut Wiśniowiecki, Lithuanian: Mykolas I Kaributas Višnioveckis; May 31, 1640 – November 10, 1673) was the ruler of the Polish–Lithuanian Commonwealth as King of Poland and Grand Duke of Lithuania from September 29, 1669 until his death in 1673. Michael's reign was marked by struggles between the pro-Habsburg and pro-French political factions. A native Pole and descendant of Korybut, brother of King Władysław II Jagiełło, Michael was freely elected by the unanimous vote of the Polish nobility after the abdication of his predecessor, John II Casimir Vasa. Chosen partly because of the merit of his father, Prince Jeremi Wiśniowiecki, a powerful border magnate who had helped suppress the Cossacks in eastern Poland during the Khmelnytsky Uprising, Michael proved to be a passive tool in the hands of the Habsburgs. In view of this, the French party rallied round John Sobieski, a rising military commander. The dissensions between the two camps led to defeat at the hands of the united Turks and Cossacks and the signing of the Treaty of Buchach in 1672, by which all Polish-occupied Ukraine came under Turkish suzerainty. After Michael's early death, these setbacks were reversed at the Battle of Khotyn in 1673 by his successor, John III Sobieski, who defeated an Austrian candidate in the election. In 1670 Michael I was married to Eleonora Maria of Austria (1653–1697), daughter of Ferdinand III, Holy Roman Emperor, by his third wife Eleonora Gonzaga. Michael was the son of Jeremi Wiśniowiecki and his wife Gryzelda Konstancja Zamoyska. His parents likely met each other in September 1637 in Warsaw during the crowning of Cecilia Renata of Austria, the Queen of Poland and consort to Władysław IV. They were engaged on February 13, 1638, over a month after the death of Gryzelda’s father, Tomasz Zamoyski. The wedding took place in Zamość on February 27, 1639, and over a year later, on May 31, 1640, Michael Korybut was most likely born in the village of Biały Kamień as Michał Tomasz Wiśniowiecki. The infant was then taken to Zamość, where he spent first two years of his life under care of his grandmother Katarzyna Zamoyska (née Ostrogska). In 1642, Michał was taken by his mother to Lubny. During the Khmelnytsky Uprising, he fled Left-bank Ukraine with his family and first settled in Wiśniowiec in Volhynia, before arriving in Zamość in autumn 1648. On 16 September 1668, John II Casimir abdicated the Polish throne and left the country to live in France, making a new election necessary. The Bishop of Chełmno, Andrzej Olszowski, suggested that Michał Korybut should be listed as one of candidates for the throne. Wiśniowiecki was supported by the Polish nobility, who sensed that a poor and inexperienced prince would not pose a threat to their rights enshrined in the Golden Liberty. The Free election of 1669 took place in May and June of that year. Michał Korybut Wiśniowiecki was elected King of Poland and Grand Duke of Lithuania on June 19 and became known as Michael I. Most of the gathered nobility voted for him as they wished to choose a native, Polish candidate (the so-called "Piast"), over foreign candidates. Wiśniowiecki won 11 271 votes and was crowned on September 29, 1669 in Kraków.

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