 Diane de Poitiers was the unquestioned mistress of the castle, but ownership remained with the crown until 1555, when years of delicate legal maneuvers finally yielded possession to her.After King Henry II died in 1559, his strong-willed widow and regent Catherine de' Medici forced Diane to exchange it for the Château Chaumont.Queen Catherine then made Chenonceau her own favorite residence, adding a new series of gardens.