liberating army, he gave his consent to the most humiliating terms, and solemnly pledged himself not to repudiate the agreement. By it he was to win the consent of the Emperor and Electors, and to withdraw all foreign troops from the Netherlands within eight days. He renounced, for Flanders, the guardianship of Philip, and acceded to the formation of a Council of Regency and to a peace with France (May 16). On the strength of these promises he was liberated, and joined his father's army at Liège. Frederick and the Princes refused to recognize any such agreement; it was declared invalid and contrary to his coronation oath, on the ground that the Flemings were subjects {22} of the Empire;[25] and Maximilian, weakly yielding to their pressure, contented himself with returning the 55,000 groschen which had been granted him to lessen the bitterness of the pill. The march was resumed, and Ghent was closely invested. But as usual the old Emperor effected little or nothing, the town made a vigorous defence, and Maximilian was glad to avail himself of events in Germany, which claimed his attention. It is useless to attempt to justify his repudiation of his oath, for he had carefully precluded himself from all lawful methods of evasion. It leaves a deep stain upon his honour, and the most that can be said for him is that it is the one indefensible action of his life. After an absence of twelve years[26] Maximilian returned to the Empire in December 1488, leaving Duke Albert of Saxony as his representative in the Netherlands. The latter showed his zeal by his promise "so to serve his master that men should write of it for 1,000 years," and displayed great ability both as a commander and an organizer. The cause of peace was furthered by the Treaty of Frankfort (July 7, 1489), in accordance with which Charles VIII. was to use his influence with the Flemings, and an interview was to be arranged between him and Maximilian for the settlement of the Burgundian question. As a result of this treaty, Flanders again recognized Maximilian as lawful Regent and guardian of his son, and granted him the sum of 300,000 gold thalers in token of their submission.