He finally laid siege to the great seaport of Antwerp. The town was open to the sea, strongly fortified, and defended with resolute determination and courage by its citizens. They were led by the famous Marnix van St. Aldegonde and assisted by an ingenious Italian engineer named Federigo Giambelli. The siege began in 1584 and called forth all of Farnese's military genius. He cut off all access to Antwerp from the sea by constructing a bridge of boats across the Scheldt from Calloo to Oordam, in spite of the desperate efforts of the besieged townspeople. The terms offered included the clause that all Protestants had to leave the city within four years. This disciplined capture and occupation of the town should not be confused with the bloody events of the Spanish Fury on 4 November 1576. Farnese avoided the mistakes of his predecessor Don Luis de Requesens. With the Fall of Antwerp, and with Mechelen and Brussels already in the hands of Farnese, the whole of the southern Netherlands was once more placed under the authority of Philip. At one stage Holland and Zeeland, whose geographical position made them unassailable except by water, were hard pressed to retain territory. The poorly supplied English forces, sent by Elizabeth I, were duly defeated by the Duke's.