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Chief minister of France – Diplomacy

The succession of Mazarin to the position of chief minister of Louis XIII was not automatic or immediate. Despite the accounts of some later historians, Richelieu did not name Mazarin as his successor. Richelieu did, according to Mazarin himself, advise the King to employ Mazarin, who until that time had no official position at court.

After the death of Richelieu, Louis XIII named three prominent figures to advise him; François Sublet de Noyers, Léon Bouthillier, comte de Chavigny and Mazarin. Mazarin and de Chavigny immediately joined together to get rid of de Noyers. They hinted to the King that de Noyers had secretly made an agreement with Anne of Austria to make her the regent of France after the King's death. The King, who had little love for the Queen and in his will had refused to make her his regent, was furious; de Noyers was forced to resign on 10 April 1643.

Louis XIII died 14 May 1643, just five months after Richelieu. His successor, Louis XIV, was just four years old. The King had specifically instructed that his wife, Anne of Austria, not rule in his place as regent. However, as soon as he was dead, she applied to the body of nobles known as the Parlement of Paris, and had his will annulled. She was declared Regent on 18 May. The Queen had a particular dislike of de Chavigny, the other chief advisor chosen by Louis XIII. He had been close to Richelieu and was the only real rival in experience to Mazarin. The evening that she became regent, she declared that Mazarin would be her chief minister and head of her government.

The management style of Mazarin was entirely different from that of Richelieu. The contrast was described by Cardinal Retz, the future enemy of Mazarin, in his Memoires: "One saw on the steps of the throne, where the sharp and fearsome Richelieu had thundered rather than governed the people, a leader who is gentle, benevolent, and demands nothing...He has the spirit, the insinuation, the playfulness, the manners, but also a certain laziness...."

Cardinal Retz and other rivals in the court underestimated Mazarin's skills, energy and determination. Mazarin continued Richelieu's costly war against the chief rivals of France in Europe, the Habsburgs of Austria and Spain. The victories of Condé and Turenne finally brought Austria to the bargaining table and ended the Thirty Years' War with the Peace of Westphalia (1646–48)

Mazarin's policies also added Alsace (though not Strasbourg) to France. He settled Protestant princes in secularized bishoprics and abbacies in reward for their political opposition to the Habsburgs, building a network of French influence as a buffer in the western part of the Empire. In 1657, he made an attempt to get Louis XIV elected as Holy Roman Emperor. In 1658 he formed the League of the Rhine, which was designed to check the House of Austria in central Germany. In 1659 he made peace with Habsburg Spain in the Peace of the Pyrenees, which added to French territory Roussillon and northern Cerdanya—as French Cerdagne —in the far south as well as part of the Low Countries.

Towards Protestantism at home, Mazarin pursued a policy of promises and calculated delay to defuse the armed insurrection of the Ardèche (1653), for example, and to keep the Huguenots disarmed: for six years they believed themselves to be on the eve of recovering the protections of the Edict of Nantes, but in the end they obtained nothing.

There was constant friction with the pontificate of the Spanish Cardinal Pamphilj, elected pope on 15 September 1644 as Innocent X. Mazarin protected the Barberini cardinals, nephews of the late pope, and the bull against them was voted by the Parlement of Paris "null and abusive"; France made a show of preparing to take Avignon by force, and Innocent backed down. Mazarin was more consistently an enemy of Jansenism, in particular during the formulary controversy, more for its political implications than out of theology. On his deathbed he warned young Louis XIV "not to tolerate the Jansenist sect, not even their name." After his death, Louis XIV did not appoint a new principal minister and instead governed himself, marking the beginning of a new era of centralized government in France.