The long-running contest with Spanish and Austrian Habsburgs led to French involvement in the 1568-1648 Dutch Revolt and peripheral engagements of the 1618-48 Thirty Years War. During the 1627-1630 War of the Mantuan Succession, Charles' eldest son and namesake died in 1630 at Chambéry, the capital of Savoy and he himself was killed in 1638 at Breme in Lombardy. Charles served under his father-in-law, the duc de Lesdiguières, in the 1600-1601 Franco-Savoyard War and was appointed Colonel of the Gardes Françaises in 1605. When Henry IV was assassinated in 1610, his son Louis XIII was only nine years old and his mother, Marie de Medici became Regent. Her concern at having the Protestant Lesdiguières as Governor of the Dauphiné led to his replacement in 1612 by Charles. France regularly became involved in Italian disputes given its proximity to the Duchy of Savoy, which then included the modern French territories of Villefranche and the County of Savoy. In addition, control of Northern Italy allowed the Habsburgs to threaten the French provinces of Languedoc and the Dauphiné and control supply routes over the Alpine passes. The capture of the Huguenot stronghold of La Rochelle in 1628 released French forces for the relief of Casale Monferrato, then besieged by a Habsburg army during the War of the Mantuan Succession. In March 1629, the French stormed barricades blocking the Pas de Suse and lift the siege of Casale; after agreeing the Treaty of Susa with Savoy in April, the French evacuated the area, leaving a garrison at the strategic fortress of Pinerolo. Some of his letters are preserved in the Bibliothque Nationale in Paris, and his life was written by N. Chorier (Grenoble, 1683)