By the terms of the Treaty of Viterbo, the Angevins of the Kingdom of Naples had inherited the Principality of Achaea upon the death of William II Villehardouin in 1278. They had, for some time, granted it to William's older daughter, Isabella of Villehardouin, to rule. However, they remained feudal overlords of the Principality and retook in 1307, due to the misgovernment of Isabelle's husband Philip of Savoy. In 1312, on the death of Isabelle, her younger sister, Margaret, claimed the Principality under the terms of her father's will, which conflicted with the Treaty of Viterbo.