The Franco-Spanish War (1635–1659) was fought between France and Spain, with the participation of a changing list of allies through the war. The first phase, beginning in May 1635 and ending with the 1648 Peace of Westphalia, is considered a related conflict of the Thirty Years' War. The second phase continued until 1659 when France and Spain agreed to peace terms in the Treaty of the Pyrenees.
France avoided direct participation in the Thirty Years' War until May 1635 when it declared war on Spain and the Holy Roman Empire, entering the conflict as an ally of the Dutch Republic and Sweden. After Westphalia in 1648, the war continued between Spain and France, with neither side able to achieve decisive victory. Despite minor French gains in Flanders and along the north-eastern end of the Pyrenees, by 1658 both sides were financially exhausted and made peace in November 1659.
French territorial gains were relatively minor in extent but significantly strengthened its borders in the north and south, while Louis XIV of France married Maria Theresa of Spain, eldest daughter of Philip IV of Spain. Although Spain retained a vast global empire until the early 19th century, the Treaty of the Pyrenees has traditionally been seen as marking the end of its status as the dominant European state and the beginning of the rise of France during the 17th century.