The time was now at hand for the campaign to commence: and Henry proposed a modification of the original scheme. According to his view, it would be better for the two armies to concentrate in force on the frontiers while a single detachment penetrated as far into France as might seem wise. Charles however insisted on his plan of two separate invasions. Henry could not refuse, but pointed out that his own march on Paris was conditioned by the thorough reduction of the country as he advanced; notably of Boulogne and Montreuil which would otherwise perpetually threaten his communications. The English proceeded to lay siege to these two places, and the Emperor attacked St. Dizier. Until these strongholds were captured, the two armies were respectively unable to advance. With August, Francis renewed his scheme of making separate overtures accompanied by suggestions to each monarch that his ally was trying to make terms for himself. Each again refused to treat apart from the other. At last St. Dizier fell, and Charles advanced into France, passing by Chalons and a considerable French army which was enabled to act on his line of communications. Hence he very soon found himself in grave difficulties. Thereupon he informed Henry that unless the English marched straight upon Paris, regardless of Boulogne and Montreuil, (which he knew to be strategically impossible) he would have to accept for himself the terms offered by Francis. Boulogne was taken (September 14th) three days after the message was received, but Montreuil held out. Henry had honourably refused to make terms for himself; but on September 19th Charles signed the peace of Crepy--amounting to a simple desertion of his ally. Boulogne was lost to the French, and though they were now free to concentrate their forces against the English, all attempts to re-capture it were repulsed. Henry felt no disposition to abate his own terms or to resign Boulogne: Francis required him to do both. Charles politely repudiated any obligation to armed intervention, despite the efforts of Gardiner to persuade him--much to the bishop's disappointment, since the Lutheran Princes, alarmed by the Emperor's conduct, were again making overtures to England. [Sidenote: 1545 Ancram Moor]