|Centuries:||16th century – 17th century – 18th century|
|Decades:||1610s 1620s 1630s – 1640s – 1650s 1660s 1670s|
|Years:||1640 1641 1642 – 1643 – 1644 1645 1646|
- January 21 – Abel Tasman discovers Tonga
- February 6 – Abel Tasman discovers the Fiji islands.
- May 19 – Battle of Rocroi: French victory over the Spanish at Rocroi, France.
- July 13 – English Civil War: Battle of Roundway Down – In England, Lord Henry Wilmot, Earl of Rochester, commanding the Royalist forces, wins a crushing victory over the Parliamentarian Sir William Waller.
- An Calbhach mac Aodha O Conchobhair Donn inaugurated as the last king of Connacht
- Austro-Bavarian army defeats French at Duttlingen.
- The Royalist forces supporting Charles I in the English Civil War win the Battle of Adwalton Moor and gain control of Yorkshire.
- End of the reign of Empress Meisho of Japan
- Emperor Go-Komyo ascends to the throne of Japan
- Evangelista Torricelli invents the mercury barometer
- New England Confederation is formed
- Battle of Tüttlingen fought
- Baden-Baden pillaged by the French
- John Colgan published the first two volumes of the Acta Sanctorum
- Paul Chomedey de Maisonneuve places the first cross atop Mount Royal
- Åmål is granted its city charter
- Miyamoto Musashi dictates The Book of Five Rings (Go Rin No Sho) to his student, completing it in 1654 just before his death
- Hong Taiji, Emperor of the Qing Dynasty of the Manchu dies and is succeeded by his five-year-old son, the later Shunzhi Emperor of China.
- Roger Williams, a co-founder of Rhode Island, publishes A Key Into the Language of America
- Evangelista Torricelli invented the Barometer.
- January 4 – Sir Isaac Newton, English scientist (d. 1727)