The strange inactivity and want of interest, which Maximilian would at first sight seem to have displayed, while such grave issues were at stake, must be attributed to an event of great importance in the history of his own dominions. This was no less than his reception, at Vienna, of the Kings of Hungary and Poland, which set a seal to the negotiations and labours of many years by a final understanding between the two dynasties.[86] Under the terms of the Treaty of Vienna (July 22), Prince Louis of Hungary was definitely betrothed to Mary of Austria, while his sister Anne was delivered over to the Emperor to be educated, in view of her marriage with the young Archduke Ferdinand. The flattery and congratulations which surrounded these proceedings included the adoption of Louis by Maximilian as his successor in the Empire. But this was merely a formal move in the diplomatic game, calculated to {70} win the support of the young Prince. The Emperor well knew that the Electors cared little for any wishes which he might express; otherwise we may be sure that Charles, not Louis, would have been designated.[87] The completeness of Francis's success, and his efforts to rouse the Scots against England drove Henry VIII. into the arms of Ferdinand. (October 19.) English gold was liberally expended among the Confederates; and in February, 1516, 17,000 Swiss mercenaries moved on Verona, to join the Imperialists. Maximilian, whose forces were further swelled by levies of Tyrol and the Swabian League, was thus enabled to take the offensive in North Italy, with better prospects of success than on any previous occasion. In March he led a well-appointed army of 30,000 men across the Mincio, and forced the French and Venetians to raise the siege of Brescia and fall back upon their respective bases. Maximilian continued to advance rapidly beyond the Oglio and the Adda, until he was within nine miles of Milan itself. But now, when Bourbon was well-nigh incapable of any prolonged resistance, and when fortune, after so many rebuffs, seemed at length about to crown the Imperial arms with victory, Maximilian, for some inexplicable reason, hesitated to strike home, and withdrew his army once more behind the Adda. His motives for so extraordinary a step have never been discovered; and today we are as completely in the dark as were his own allies at the time. Pace, who, as English envoy in Maximilian's camp, had peculiar opportunities for clearing up the mystery, writes in {71} his report to Wolsey, "that no man could, ne can, conject what thing moved him to be so slack at that time, when every man did see the victory in his hands, and the expulsion of the Frenchmen out of Italy."[88] Maximilian's own version--that the difficulties of foraging, the enemy's superiority in cavalry, and the stoppage of English money necessitated a retreat--is, in the face of incontestable facts, most improbable; and the only plausible