Ably assisted by Maximilien de Béthune, duc de Sully, Henry reduced the land tax known as the "taille"; promoted agriculture, public works, construction of highways, and the first French canal; started such important industries as the tapestry works of the Gobelins; and intervened in favor of Protestants in the duchies and earldoms along the German frontier. This last was to be the cause of his assassination. Henry's marriage to Margaret, which had produced no heir, was annulled in 1599 and he married Marie de Medici, niece of the grand duke of Tuscany. A son, Louis, was born to them in 1601. Henry IV was assassinated on 14 May 1610 in Paris. Louis XIII was only nine years old when he succeeded his father. He was to prove a weak ruler; his reign was effectively a series of distinct regimes, depending who held the effective reins of power. At first, Marie de Medici, his mother, served as regent and advanced a pro-Spanish policy. To deal with the financial troubles of France, Louis summoned the Estates General in 1614; this would be the last time that body met until the eve of the French Revolution. Marie arranged the 1615 marriage of Louis to Anne of Austria, the daughter of King Philip III of Spain. In 1617, however, Louis conspired with Charles d'Albert, duc de Luynes to dispense with her influence, having her favorite Concino Concini assassinated on 26 April of that year. After some years of weak government by Louis's favorites, the King made Armand Jean du Plessis, Cardinal Richelieu, a former protégé of his mother, the chief minister of France in 1624. Richelieu advanced an anti-Habsburg policy. He arranged for Louis' sister, Henrietta Maria, to marry King Charles I of England, on 11 May 1625. Her pro-Catholic propaganda in England was one of the contributing factors to the English Civil War. Richelieu, as ambitious for France and the French monarchy as for himself, laid the ground for the absolute monarchy that would last in France until the Revolution. He wanted to establish a dominating position for France in Europe, and he wanted to unify France under the monarchy. He established the role of "intendants", non-noble men whose arbitrary powers of administration were granted (and revocable) by the monarch, superseding many of the traditional duties and privileges of the noble governors.