In the year AD
- The Thirty Years' War lumbers on into its 20th year, with the Protestants securing several stunning victories.
- French-backed German Protestant prince Bernhard of Saxe-Weimar embarks on an eight-month siege of the mighty Imperial fortress at Breisach on the upper Rhine, beating back several attempts by Imperial forces to reinforce the citadel before finally starving out the defenders and capturing the town in December, bringing a decisive end to the war on the Rhine in favor of the Protestants.
- After Swedish attempts to secure a separate peace with the Holy Roman Empire collapse, the Swedes are desperate for money and barely clinging to their meager holdings in Pomerania. Out of other options, Swedish statesman Axel Oxenstierna once again turns to Cardinal Richelieu and the French, signing the Treaty of Hamburg, which renews the Franco-Swedish alliance for another three years and pledges the French to continue to pay the Swedish the annual subsidy of 1 million livres for the duration.
- Now flush with French cash, Axel Oxenstierna sends the brilliant Swedish general Johan Banér 14,000 freshly-recruited stout young Swedes as reinforcements. Banér heads east, clearing Mecklenburg and Pomerania of Imperial troops, and then presses through Silesia and into Bohemia, driving the beleaguered Austrian forces under Matthias, Graf von Gallas into full-on retreat.
- Meanwhile, Karl-Ludwig, the eldest son and successor of Frederick the Winter King conceives of a quixotic plan to recover the Palatinate. Securing funds from English king Charles I, he raises and army and attacks along the River Ems, but is promptly met and annihilated at the Battle of Hochfeld, ending yet another short and sorry chapter in the history of Karl-Ludwig's feckless house and ineffective Stuart diplomacy.
- Forces loyal to the Tokugawa Shogunate crush the last resistance at Hara Castle, bringing an end to the Shimabara Rebellion.
- A diverse group of Scotsmen unite in February to produce the National Covenent, a manifesto against English king Charles I's attempts to interfere with the Scottish Church. In November, these "Covenanters" vote to expel all the Anglican bishops from the Scottish church, making Scotland officially Presbyterian, and leading to the first of the "Bishops' Wars" the following year when Charles attempts to enforce his will by sending in an army.
- Ottoman Sultan Murad IV retakes Baghdad from the Persians after a bloody 40-day siege.
- After a lengthy trial, Anne Hutchinson is convicted of blasphemy and "lewd and lascivious conduct" and is excommunicated and banished from the Massachusetts Bay Colony. She and her family relocate to the newly founded colony of Rhode Island.
- On the morning of Sunday, October 21, during a severe thunderstorm in the English town of Widecombe-in-the-Moor, a giant ball of fire 8 feet in diameter strikes a church packed with 300 worshippers, destroying much of the church, killing 4 and injuring 30. At the time the giant ball of fire is alternately speculated to be the wrath of God or the work of the Devil, but today is best known as one of the most famous cases of ball lightning.
- Shipwrecked English sailors found the first European settlement in what is now Belize.
- Dutch colonists establish the first European settlement on the island of Mauritius.
- Swedish settlers establish the first European settlement in what is now the state of Delaware, calling it "New Sweden."
- The Finnish postal service, Suomen Posti, is established.
- Puritan settlers led by Theophilus Eaton and John Davenport found the city of New Haven, Connecticut.
- The construction of the Taj Mahal is completed.
- Galileo's last book Dialogues Concerning Two New Sciences, which contains most of his contributions to Physics, is published.
These people were born in 1638...
These people died in 1638...
1637 - 1638 - 1639