The deaths of his three older brothers Roger, Tancred, and Alfonso between 1138 and 1148 changed matters, though when his father died William was still not well-prepared to take his place.
Kematian tiga kakandanya: Ruggeru, Tancredi, dan Alfonso di antara tahun 1138 dan 1148 mengubah hal-hal, meski ketika ayahandanya meninggal Gugghiermu masih belum siap untuk menggantikannya.