War of Devolution
In the 1667 to 1668 War of (the) Devolution, France occupied the Spanish-controlled provinces of Spanish Netherlands and Franche-Comté. Because of one law not many people knew about (called the Jus Devolutionis), Louis XIV claimed these provinces 'devolved' to him because of his marriage to Maria Theresa of Spain.
King Louis had claimed territory from the Spanish Empire as his own, due to his marriage of Maria Theresa. This claim started the conflict between France and the Spanish Empire. The Triple Alliance, (England, Sweden, and The Netherlands,) decided to get involved in this war, but not allying with either side. They saw 2 countries now weakened by war and realized they could expand. They also did this for the protection of each side, because both were a vital piece to trade in Europe and the world. The French soldiers marched into Flanders, (now in Belgium) and easily took over the city. Just a year later after almost a standoff, they made a peace treaty with Holy Roman Emperor Leopold I. They would partition the Spanish Dominions until the king's death, and France would annex part of the Netherlands.
- Brittanica: War of Devolution