A few years later, however, an opportunity presented itself of dealing a blow at the Austro-Spanish House in a less original but equally effective way. In 1609 John William,[1] duke of Cleves, Jülich, and Berg died without children, and the right of succession was claimed by two princes. John Sigismund, the elector of Brandenburg, whose wife was the child of the eldest daughter of William the Rich, brother and predecessor of the last duke, rested his wife’s claim partly on his descent from the elder branch, and partly on a will made by William the Rich in which he gave the descendants of the elder daughter preference over those of the younger. The count palatine of Neuburg had married a younger daughter of William the Rich, who claimed the inheritance as being the nearest of kin. The eldest sister of John William being dead, she made over her claim to her son Wolfgang William. The question was therefore mainly the old one of the eldest by descent against the nearest of kin, and was eminently one for the imperial courts to decide. But the matter was complicated by religious considerations. The three duchies lay along the course of the lower Rhine from the frontiers of the United Provinces nearly to Andernach, enclosing within their embraces a considerable part of the archbishopric of Köln. The population was Catholic but both the claimants were Lutherans, and on the principle of _cujus regio ejus religio_, laid down by the religious peace of Augsburg, if the duchies passed into Lutheran hands, there was a strong probability that they would before long not only become Lutheran themselves, but drag the vacillating archbishopric of Köln with them. The Emperor, Rudolf, in order to guard against this danger, at once claimed the right of administering the duchies until the question of the succession was settled, and sent an army to occupy Jülich. But if the Catholics could not permit the duchies to fall into Lutheran hands, still less could Protestant or French interests see unmoved the imperial armies encamped on the borders of the United Provinces, in close proximity to the frontiers of France and the Spanish Netherlands. An imperial army on the lower Rhine was a menace alike to north German Protestantism, to the hardly won Dutch independence, and to English and French jealousy. [Sidenote: =League under Henry IV. against the Emperor, 1610.=]