Diane de Poitiers 9 January — 25 April was a French noblewoman and courtier who wielded much power and influence as King Henry II 's royal mistress and adviser until his death. Her position increased her wealth and family's status. She was a major patron of French Renaissance architecture. Like her fellow charges, Diane was educated according to the principles of Renaissance humanism , including Greek and Latin , rhetoric , etiquette, [ 2 ] finance, law, and architecture.
Shortly after her marriage, Diane became lady-in-waiting to Queen Claude of France. In , her husband uncovered Constable Charles de Bourbon 's plot against King Francis I, but did not know at the time that his father-in-law was involved as well. In , Jean de Poitiers was accused of treason and sentenced to death, but his sentence was commuted.
He instead was confined to prison until the Treaty of Madrid in After her husband died in in Anet , [ 5 ] Diane adopted the habit of wearing black and white for the rest of her life. 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 seneschal 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 their considerable revenues.
