succession to the Imperial crown, and his election to the dignity of King of the Romans. In such an event the Empire and his vast dominions would pass together at his death to Maximilian, and the aim of the Austrian House would be realized. It was to negotiate this marriage, a marriage which in the end was destined to shape the political map of modern Europe, that Duke and Emperor met in 1473 at Trier. [Sidenote: Peace with France] But if Frederick's policy was to strengthen his house the policy of the princes of the Empire lay in keeping it weak; and their pressure was backed by suspicions of the Duke's treachery, and of the possibility of a later marriage whose male progeny might for ever exclude the house of Austria from the Imperial throne. Frederick's sudden flight broke up the conference; but Charles was far from relinquishing his plans. To win the mastery of the whole Rhine valley was the first step in their realization, and at the opening of 1474 he undertook the siege of Neuss, whose reduction meant that of Koeln and of the central district which broke his sway along it. But vast as were the new dreams of ambition which thus opened before Charles, he had given no open sign of his change of purpose. Lewis watched his progress on the Rhine almost as jealously as his attitude on the Somme; and the friendship of England was still of the highest value as a check on any attempt of France to interrupt his plans. With this view the Duke maintained his relations with England and fed Edward's hopes of a joint invasion. In the summer of 1474, on the eve of his march upon the Rhine, he concluded a treaty for an attack on France which was to open on his return after the capture of Neuss. Edward was to recover Normandy and Aquitaine as well as his "kingdom of France"; Champagne and Bar were to be the prizes of Charles. Through the whole of 1474 the English king prepared actively for war. A treaty was concluded with Britanny. The nation was wild with enthusiasm. Large supplies were granted by Parliament: and a large army gathered for the coming campaign. The plan of attack was a masterly one. While Edward moved from Normandy on Paris, the forces of Burgundy and of Britanny on his right hand and his left were to converge on the same point. But the aim of Charles in these negotiations was simply to hold Lewis from any intervention in his campaign on the Rhine. The siege of Neuss was not opened till the close of July, and its difficulties soon unfolded themselves. Once master of the whole Rhineland, the house of Austria saw that Charles would be strong enough to wrest from it the succession to the Empire; and while Sigismund paid back his loan and roused Elsass to revolt the Emperor Frederick brought the whole force of Germany to the relief of the town. From that moment the siege was a hopeless one, but Charles clung to it with stubborn pride through autumn, winter, and spring, and it was only at the close of