In 1204 Athens was fiercely sacked by the Franks of Boniface de Montferrat and became the feud of Otto de la Roche from Burgundy. He gave Daphni to the Cistercian monks from the Bellevaux abbey in Burgundy, in 1207. Cistercians are an austere branch of the Benedictines, formed in 1098 by Robert in Citeaux, a city in Burgundy. They actively participated in the Crusades and were probably given Daphni as a reward. Orthodox monks had to leave and the Cistercians stayed for two and a half centuries, unaffected by the Catalan (1311-1388) and then Florentine occupations (1387-1458). They only were expelled by the Ottomans of Mehmed II, when the monastery became orthodox again. Frankish documents and inscriptions mention the monastery, which is also supposed to have been the duchal burial place. The duchal mausoleum was assumed to have been in the crypt under the narthex. However, this is only a hypothesis.
Although the Cistercians did not usually occupy monasteries of other orders, they settled in Daphni and
did few changes and additions, such as the repair of the exonarthex in the late 13th – early 14th century, which had collapsed due to earthquakes. Its upper floor became a defensive stronghold with bastions. The narthex crypt became a mausoleum, while a series of cells was built to the south of the catholicon. Finally, oral tradition
inaccurately connects Daphni with the murder of Chiara Giorgi, last duchess of Athens, by her nephew, the Florentine Francesco II Acciajuoli, last duke before the Ottoman conquest in 1458.
Outer view of the northern section of the Daphni Monastery defensive wall (photo by Sp. Panagiotopoulos).