1644 (MDCXLIV in Roman numerals) is a leap year of the 17th century.
Francesco Pellizzari publishes his first work, Tractatio De Monialibus, dedicated to the economy of convents and monasteries and to the legal discipline of the same.
Collapse of the Ming dynasty in China by the Manchu warriors and establishment of the Qing dynasty, which will reign over the country until 1912.
The Ottoman Empire of Ibrahim I, breaking a truce that lasted from the battle of Lepanto (1571), assaults the island of Crete and conquers the fortress of Chania from the Republic of Venice.
In France, several peasant revolts broke out due to the excessive tax burden in the Provinces of Dauphiné, Languedoc, Normandy and Armagnac.
French peacekeepers arrive in Munster to put an end to the Thirty Years' War with Ferdinand III's Holy Roman German Empire. During the peace talks, the French army of the regent Anne of Austria on behalf of the 6-year-old son King Louis XIV, conquers the cities of Philippsburg, Mainz, Mannheim, Speyer, Worms and Oppenheim.
March 31: the Peace of Ferrara is signed which puts an end to Castro's first war. Pope Urban VIII must return the Duchy to the Farnese family, former dukes of Parma.
July 1 - Naval Battle of Colberger Heide in the Torstenson War: the Danish fleet, directly commanded by King Christian IV, defeats the Swedish one whose commander dies in battle.
2 July - Battle of Marston Moor: in the context of the English civil war, the Parliamentarians inflict a decisive defeat on the Royalists of King Charles I Stuart.
September 15: Giovanni Battista Panphili at the age of 70 is elected 236th Pope with the name of Innocenzo X.
23 October - Naval Battle of Fehmarn as part of the Torstenson War: the Swedish fleet, under the command of Major General Carl Gustaf Wrangel, who took over from Fleming who died in the battle of Colberger Heide on 1 July, takes revenge and defeats the Danish fleet .
December 18: at the age of 18, Queen Christina of Sweden, in office since 1632, directly assumes the government of the nation that she will hold until 1654.
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