During the French Wars of Religion, Henry IV of France declares war on Spain.

The French Wars of Religion were a series of civil wars between French Catholics and Protestants from 1562 to 1598. Between two and four million people died from violence, famine or disease directly caused by the conflict, and it severely damaged the power of the French monarchy. One of its most notorious episodes was the St. Bartholomew's Day massacre in 1572. The fighting ended with a compromise in 1598, when Henry of Navarre, who had converted to Catholicism in 1593, was proclaimed King Henry IV of France and issued the Edict of Nantes, which granted substantial rights and freedoms to the Huguenots. However, Catholics continued to disapprove of Protestants and of Henry, and his assassination in 1610 triggered a fresh round of Huguenot rebellions in the 1620s.

Henry IV, also known by the epithets Good King Henry or Henry the Great, was King of Navarre from 1572 and King of France from 1589 to 1610. He was the first monarch of France from the House of Bourbon, a cadet branch of the Capetian dynasty. He pragmatically balanced the interests of the Catholic and Protestant parties in France, as well as among the European states. He was assassinated in Paris in 1610 by a Catholic zealot, and was succeeded by his son Louis XIII.

January 17 is the 17th day of the year in the Gregorian calendar; 348 days remain until the end of the year.