Since the opening up of the Zuiderzee in the eleventh city, the area West Friesland (roughly the northern part of modern day North Holland) had become isolated from the rest of the Netherlands economically and politically, and its political isolation was increased after Haarlem fell to the Spanish in 1573. Interested outsiders, notably the English, saw political opportunities to weaken the authority north of Haarlem of the States General in The Hague, by encouraging separatism in West Friesland, especially following the assassination of William of Orange in 1583. Maelson's unwavering support for the Orange cause was an important element in keeping the fighters for Dutch independence united.