This event proved of the utmost importance in the history of Belgium. Although regarded as a separate territory, the Netherlands--both Belgium and Holland--became a mere annex of the Spanish branch of the Hapsburg monarchy. For more than two centuries Belgium was ruled from Madrid by sovereigns who were first of all kings of Spain. This was not yet, however, the case in the time of Charles V, the great emperor of the sixteenth century. Archduke Charles, son of Philip the Fair, known as Charles V at the time of his accession as Emperor in 1519, assumed control of the Netherlands in 1515. The latter included Belgium and Holland, in addition to the county of Artois, and was commonly spoken of as the Seventeen Provinces. The following year (1516) Charles also became King of Spain. His reign was occupied by protracted wars with France, constituting a continuous strife with the powerful sovereign for the hegemony of Europe. In the course of this struggle the Netherlands were continually attacked by Francis I, the French King, and his allies, the Duke of Gueldre, and the La Marcks, Lords of Sedan and Bouillon. The advantage was always with Charles, however, and he was thus enabled to continue the territorial concentration of all the provinces of the Netherlands which was begun by the dukes of Burgundy. Peacefully or by force, Charles successively annexed East Friesland, Tournai and Tournaisis, the Overyssel, Groninge and Ommelanden, Gueldre and Zutphen to his domains. In the ecclesiastical principalities, which the Burgundian dukes had never been able to annex but only to control, Charles succeeded in winning the temporal power in the bishopric of Utrecht; destroyed Térouanne, the seat of the bishopric of the same name; erected Cambrai and Cambrésis into a duchy in favor of the bishop; and purchased part of the principality of Liège, where he built strong fortresses. After these achievements, Charles V could call himself the mightiest sovereign in Europe. But a very intricate question yet remained to be settled, namely, what the political relation of the Netherlands should be toward the Empire. The feudal tie between the Empire and the provinces, called into existence while Lotharingia was yet a fief, had never, theoretically at least, been broken; and at the beginning of the sixteenth century Germany still affected to recognize the union (the feudal vassalage) of the provinces with the Empire, in order that they might be the more easily compelled to share in the heavy financial burdens of the latter. The Netherlands, on the other hand, maintained that the union no longer existed. The question was a difficult one for Charles, he being at the same time German Emperor and sovereign of the Netherlands. It took him twenty-five years of negotiations. In 1548, after his victory over the princes of the Protestant League at Schmalkalden, he settled the question by the celebrated Augsburg transaction.