A record preserved at NivellesAdditamentum Niuialense de Fuilano, ed. Bruno Krusch, Monumenta Germaniae Historica, SRM IV, (Hannover 1902), p. 449-451. shows that Foillan and his brethren (including Ultan) fled the Kingdom of East Anglia with the help of King Anna of East Anglia in 651, when the monastery was under attack from King Penda of Mercia, and King Anna himself was then exiled from his own kingdom. Foillan and Ultan took away the precious property and books of the monastery, and after unhappy dealings with Erchinoald they were received by Ste Gertrude of Nivelles and her mother Itta. Foillan went off to found a monastery at Fosse (now Fosses-la-Ville) near Namur with the encouragement and support of Itta, but was murdered with some companions not long afterwards by bandits, during a journey from Nivelles to Fosse.Compare Bede H.E., and Whitelock 1972.
