France was a dominant power in Europe during the 17th century, which was period of consolidation of French territory and acquisition of feudal territories, commencing in 1601 when Henry IV of France intervened against the Duke of Savoy, who had been plotting against him. By the Treaty of Lyon France acquired territory north of Lyon, which comprised the modern department of Ain. Further eastern expansion was renewed during the Thirty Years’ War; the Treaty of Westphalia (1648) confirmed French land grabs from the House of Austria, endorsing the annexation of Haut-Alsace. In 1659 the frontier with Spain was finally defined and the Treaty of Pyrenees confirmed the French recovery of the territories of Roussillon and Artois The War of Devolution (1667–68), when French armies overran the Spanish Netherlands and were driven back by the combined armies of England, Sweden and the Dutch Republic, left the French with a foothold in Flanders. Louis XIV now emerged as the most powerful monarch in Europe, an aggressively expansionist absolute ruler. His decision to cross the Rhine in 1688 was seen as a step too far and a powerful alliance, comprising the Holy Roman Empire, England, Savoy, the Dutch Republic and Spain, formed to thwart his expansion in a conflict that became known as the Nine Years’ War (1688–97). In 1697 at the Treaty of Ryswik, Louis retained Alsace, but was forced to surrender Lorraine. Further adjustments to the French border were made following the War of the Austrian Succession (1748), which ended the rivalry between the French and Austrian monarchy, and the modern shape of France was finally achieved.