The Duke of Mayenne followed him with an army of thirty thousand men. He had promised to the Parisians to throw the "Bearnese" into the sea, or to bring him in chains to Paris, But it was not so easy to catch the "Bearnese." In the series of marches, countermarches, and skirmishes which is known as the battle of Arques, the advantage was on the side of the King; and when Mayenne attempted to take Dieppe by assault, he was badly defeated (Sept. 24th, 1589). Then followed marches and countermarches; the King now threatening Paris and then retreating, until at last the royalist troops and the Leaguers met at Ivry. The King had two thousand cavalry and eight thousand infantry to meet eight thousand cavalry and twelve thousand infantry (including seventeen hundred Spanish troops sent by the Duke of Parma) under the command of Mayenne. The battle resulted in a surprising and decisive victory for the King. Mayenne and his cousin d'Aumale escaped only by the swiftness of their horses (March 14th, 1590). It is needless to say much about the war or about the schemes of parties. Henry invested Paris, and had almost starved it into surrender, when it was revictualled by an army led from the Low Countries by the Duke of Parma. Henry took town after town, and gradually isolated the capital. In 1590 (May 10th) the old Cardinal Bourbon (Charles X.) died, and the Leaguers lost even the semblance of a legitimate king. The more fanatical members of the party, represented by the "Sixteen" of Paris, would have been content to place France under the dominion of Spain rather than see a heretic king. The Duke of Mayenne had long cherished dreams that the crown might come to him. But the great mass of the influential people of France who had not yet professed allegiance to Henry IV. (and many who had) had an almost equal dread of Spanish domination and of a heretic ruler. § 21. _Henry IV. becomes a Roman Catholic._ Henry at last resolved to conform to the Roman Catholic religion as the only means of giving peace to his distracted kingdom. He informed the loyalist Archbishop of Bourges of his intention to be instructed in the Roman Catholic religion with a view to conversion. The Archbishop was able to announce this at the conference of Suresnes, and the news spread instantly over France. With his usual tact, Henry wrote with his own hand to several of the parish priests of Paris announcing his intention, and invited them to meet him at Mantes to give him instruction. At least one of them had been a furious Leaguer, and was won to be an enthusiastic loyalist.