Henry IV of France
Spain and Italy

During Henry's struggle for the crown, Spain had been the principal backer of the Catholic League, and it tried to thwart Henry. Under the Duke of Parma, an army from the Spanish Netherlands intervened in 1590 against Henry and foiled his siege of Paris. Another Spanish army helped the Catholic League nobles opposing Henry to win the Battle of Craon in 1592.

The Spanish war was not ended with Henry's coronation, but after his victory at the Siege of Amiens in September 1597, the Peace of Vervins was signed in 1598. This freed his armies to settle the dispute with the Duchy of Savoy, ending with the Treaty of Lyon of 1601, which arranged territorial exchanges.

One of Henry's major problems was the Spanish Road which traversed Spanish territory through Savoy to the Low Countries. His first opportunity to cut the Spanish Road was a dispute over the ownership of the Marquisate of Saluzzo. The last marquis left Saluzzo to the French crown in 1548 (when Savoy was occupied by France), but the territory became disputed during the chaos of the Wars of Religion. The pope was asked to arbitrate between the claims of France and the Duke of Savoy. The Duke offered to cede Bresse to France if he could retain Saluzzo. Henri IV accepted this, but Spain objected that Bresse was a vital part of the Spanish Road, and persuaded the Duke to reject the decision. Henry IV was already at Lyon and had soldiers ready, and four days later he marched fifty thousand men against the duchy, occupying almost all of its area west of the Alps. In January 1601, Henry accepted another offer of papal arbitration and gained not only Bresse, but Bugey and Gex. Savoy retained a narrow corridor through the Val de Chézery. This still allowed Spanish troops to cross from Lombardy to Franche Comté without going through France, but it created a choke point where the Spanish Road was a single bridge across the Rhône River.

The Saluzzo conflict was Henry IV's last major military operation, but he continued to finance Spain's enemies. He generously assisted the Dutch Republic with over 12 million livres between 1598 and 1610. In some years, the payment was 10% of France's total annual budget. France also sent subsidies to Geneva after the Duke of Savoy attempted to capture the city in 1602.
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