The territory under nominal States-General control was steadily shrinking in other parts also. Parma seized Kortrijk in February 1580. Orange persuaded the States-General to offer sovereignty over the Netherlands to the younger brother of King Henri of France, François, Duke of Anjou, and conclude the Treaty of Plessis-les-Tours in September 1580. Anjou arrived in Antwerp in January 1581, where he took an oath to in effect govern as a "constitutional monarch", and was acclaimed by the States-General as Protector of the Netherlands.