 Owing to the friendship which united him with Erchinoald, Mayor of the Palace (who, however, expelled him from Lagny), and with the members of Pepin's family, Foillan played a significant part in Frankish ecclesiastical history, as shown by his share in the direction of Nivelles and by the foundation of the monastery of Fosses-la-Ville.It is not surprising, therefore, that he should be honoured and venerated both at Nivelles and Fosses-la-Ville and to find at Le Roeulx (Belgium) a monastery bearing his name.As late as the twelfth century the veneration in which he was held inspired Philippe de Harvengt, Abbot of Bonne-Esperance, to compose a lengthy biography of the saint.