But modify it as he might, Henry knew that such a project of union could only be carried out by a war with Francis. His negotiations for a treaty with Charles had long been delayed through Henry's wish to drag the Emperor into an open breach with the Papacy, but at the moment of the King's first proposals for the marriage of Mary Stuart with his son the need of finding a check upon France forced on a formal alliance with the Emperor in February 1543. The two allies agreed that the war should be continued till the Duchy of Burgundy had been restored to the Emperor and till England had recovered Normandy and Guienne; while the joint fleets of Henry and Charles held the Channel and sheltered England from any danger of French attack. The main end of this treaty was doubtless to give Francis work at home which might prevent the despatch of a French force into Scotland and the overthrow of Henry's hopes of a Scotch marriage. These hopes were strengthened as the summer went on by the acceptance of his later proposals in a Parliament which was packed by the Regent, and by the actual conclusion of a marriage-treaty. But if Francis could spare neither horse nor man for action in Scotland his influence in the northern kingdom was strong enough to foil Henry's plans. The Churchmen were as bitterly opposed to such a marriage as the partizans of France; and their head, Cardinal Beaton, who had held aloof from the Regent's Parliament, suddenly seized the Queen-mother and her babe, crowned the infant Mary, called a Parliament in December which annulled the marriage-treaty, and set Henry at defiance. [Sidenote: War with France.]