 Protestant Maurice was preceded as Prince of Orange (not a Dutch title) by his Roman Catholic eldest half-brother Philip William, Prince of Orange, deceased 1618.However, Philip William was in the custody of Spain, remaining so until 1596, and was thus unable to lead the Dutch independence cause.Maria of Nassau (1556–1616) was a full sister of Philip William from the first marriage of William I, Prince of Orange, (assassinated 1584), to wealthy and powerful aristocrat Anna van Egmont (1533–1558), and a contender to Maurice over the estate of their father.