Diane de Poitiers (9 January 1500 – 25 April 1566) was a French noblewoman and prominent courtier contemporary to King Francis I. She wielded much power and influence as King Henry II's chief mistress until his death. Her position increased her wealth and family's status. She was a major patron of French Renaissance architecture and a talented landowner. Diane de Poitiers was born on 9 January 1500, in Château de Saint-Vallier, Drôme, France. Her parents were Jean de Poitiers, Seigneur de Saint Vallier, and Jeanne de Batarnay. Unusually athletic, Diane kept a fit figure by riding and swimming regularly. She became a keen sportswoman, remaining in good physical condition for her time. When still a girl, Diane was briefly in the retinue of Princes Anne de Beaujeu, King Charles VIII's eldest sister who skillfully held the regency of France during his minority. Like her fellow chargers, Diane was educated according to the principles of Renaissance humanism, incluiding languages of Latin and Greek, rhetoric, etiquette, finances, laws, and architecture. On 29 March 1515, at the age of 15, Diane was married to Louis de Brézé, seigneur d'Anet, Countess of Maulévrier, and Grand Senechal of Normandy who was 39 years her senior. He was a grandson of King Charles VII by his mistress Agnès Sorel and served as a courtier to King Francis I. They had two daughters, Françoise (1518–1574) and Louise (1521–1577). Shortly after her marriage, Diane became lady-in-waiting to Queen Claude of France. After the Queen died, she served in the same capacity to Louise of Savoy, the King's mother and then Queen Eleanor of Austria. In 1523, her husband uncovered Constable Charles de Bourbon's plot against King Francis I, but didn't know at the time that his father-in-law was involved as well. In 1524, Jean de Poitiers was accused of treason and sentence to death, but his sentence was commuted. He instead was confined to prison until the Treaty of Madrid in 1526. After her husband died in 1531 in Anet, Diane adopted the habit of wearing black and white for the rest of her life. They were among the permitted colours of mourning and the symbolic colours of the sides of the moon, playing on her name which derived from the Roman moon goddess. Diane's keen interest in financial matters and legal acumen became apparent for the first time during this period. She managed to retain her late husband's emoluments as grand senechal of Normandy and challenged in court the obligation to return the family's appanages to the royal domain. Impressed, King Francis I allowed the widowed Diane to manage her inherited estates without the supervision of a male guardian and keep its considerable profits. After the capture of Francis I by Charles V's troops during the battle of Pavia (1525), the princes Francis and Henry were retained as hostages in Spain in exchange for their father. Because the ransom wasn't paid in time, the two boys (eight and seven at the time) had to spend nearly four years isolated in a bleak castle, facing an uncertain future. The experience may account for the strong impression that Diane made on Henry, as the very embodiment of the ideal gentlewomen: as his mother was already dead, his grandmother's lady-in-waiting gave him the farewell kiss when he was sent to Spain. At the tournament held for the coronation of Francis's new wife, Eleanor of Austria, in 1531, while the Dauphin of France saluted the new Queen as expected, Henry addressed his salute to Diane. In 1533, Henry was married Catherine de' Medici despite the opposition to the alliance, since the Medicis were no more than merchant upstarts in the eyes of many in the French court. However, Diane approved of the choice of bride, whom she was related to through their grandmothers. Based on allusions in their correspondence, it is generally believed that Diane became his mistress in 1534, when she was 35 years old and Henry was 15. As the couple remained childless and she became concerned by rumours of a possible repudiation of a royal wife that she had in control, Diane made sure that Henry's visits to the marital bedroom would be frequent, to the point that he had ten legitimate children. In another act of self-preservation of the royal family, Diane helped nurse Catherine back to health when she fell ill.

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