After the Byzantine fleet defeated his navy, Carlo was forced to submit, and in 1428, Glarentza was handed over as part of the dowry of his niece, Maddalena, who was married to the Despot Constantine Palaiologos (the future last Byzantine emperor). When Constantine besieged Patras in 1429, a Catalan fleet that came to the city's aid captured Glarentza, forcing Constantine to ransom it back. He then destroyed its fortifications, so that it could no longer be seized and used by a western power. In 1430, following the final subjugation of the Principality of Achaea by the Byzantines, the Peloponnese was divided into appanages among the various Palaiologos princes. Glarentza became the residence of Thomas Palaiologos until 1432, when he exchanged his portion with Constantine, who had originally settled at Kalavryta. In 1446, Glarentza and its surrounding region were raided by the Ottoman Turks under Sultan Murad II, and in 1460, it fell to the Ottomans along with the remainder of the Byzantine Peloponnese. Although nearby Chlemoutsi continued to play a role as a military stronghold until the 19th century—it was garrisoned by the Venetians during the Ottoman–Venetian War of 1463–79, and attacked by the Knights of Malta in 1620—Glarentza itself seems to have rapidly fallen into obscurity under the Ottomans, apparently declining as the maritime links with Italy were severed. By the 16th century, it was already abandoned and half-ruined. The ruins were described by successive travellers until the 19th century, and photographs were also taken later. During the German occupation of Greece in World War II, the German Army demolished many of the remains. In the early 19th century, several authors and travellers, like Robert Byron, contended that Glarentza (in its Latin form, Clarentia/Clarencia) gave its name to the royal English title of the ""Duke of Clarence"", via Princess Matilda of Hainaut and her cousin Philippa of Hainaut, a claim that has been repeated by reputable publications like the "Meyers Konversations-Lexikon" encyclopedia into the 20th century. However, this view was conclusively rejected already in 1846 by the military officer and antiquarian William Martin Leake, who pointed out that at no time did English royalty hold Moreote titles, and that "Clarence" originates from Clare, Suffolk, and not Glarentza.