A short time after the Diet most of the Protestant princes met at Ahausen and formed a confederation known as the /Union/ (1608) at the head of which stood Frederick IV. of the Palatinate, while a little later a large number of the Catholic princes bound themselves together in the /League/ and accepted Maximilian of Bavaria as their leader (1609). Thus Germany was divided once again into two hostile camps, and only a very trifling incident was required to plunge the country into another civil war. For a time it seemed as if the succession to the Duchy of Cleves was to be the issue that would lead to the catastrophe. Duke John William of Cleves had died without any direct heir, and as the religious issue was still undecided in his territory, the appointment of a successor was a matter of the greatest importance to both parties. The Emperor with the approval of the /League/ nominated his brother Leopold as administrator, while the /Union/, having strengthened itself by an alliance with France, was prepared to take the field in favour of a Protestant. Henry IV. of France, anxious to turn the disputes that had broken out between the different members of the imperial family to the advantage of himself and his country, was actually on his way to take part in the campaign when he was assassinated. On his death both parties agreed to a temporary truce (1610), and thus the outbreak of the war was delayed for some time. This delay was very fortunate for the Catholics in Germany. With such an Emperor as Rudolph pitted against a man like Henry IV. there could have been very little doubt about the issue. Even in his own territories Rudolph could not maintain his authority against his brother Matthias, in whose interest he was obliged to abdicate the throne of Bohemia (1611). On the death of Rudolph (1612) Matthias succeeded though not without considerable difficulty. As Emperor he showed himself much less favourable to the Protestants than he had been during the years when he was disputing with his brother, but, however well inclined, he was powerless to put an end to the division that existed or to control the policy of the /League/ or the /Union/. The Duchy of Cleves was still an object of dispute. While the German Protestants invoked the aid of William of Orange and the Dutch Calvinists, the Catholics called in the forces of Spain. The Emperor could merely look on while his subjects allied themselves with foreigners to settle their own domestic troubles.