erard of Groesbeck was Prince Bishop of Liège from 1563 until 1580. In 1570 De Castro dedicated his Chansons et madrigales à quatre parties to him. In the preface to this volume the composer described himself as Gerard's "buon servitore, & fidele subdito & Vassallo". Gerard of Groesbeck also acted as a patron of De Castro's friend: the Liège poet and humanist Jean Polit.
Palace of the Prince Bishop of Liège
"Hor vedi": four-part madrigal from Chansons et madrigales à quatre parties, Louvain, Phalèse, 1570, dedicated to Gerard of Groesbeck.