Having settled this important matter to his satisfaction, he again addressed himself to saving the country. During the winter, he had employed gangs of men in cutting timber in the forests, hewing it into palisades, and dragging it to Quebec. Nature had fortified the Upper Town on two sides by cliffs almost inaccessible, but it was open to attack in the rear; and Frontenac, with a happy prevision of approaching danger, gave his first thoughts to strengthening this, its only weak side. The work began as soon as the frost was out of the ground, and before midsummer it was well advanced. At the same time, he took every precaution for the safety of the settlements in the upper parts of the colony, stationed detachments of regulars at the stockade forts, which Denonville had built in all the parishes above Three Rivers, and kept strong scouting parties in continual movement in all the quarters most exposed to attack. Troops were detailed to guard the settlers at their work in the fields, and officers and men were enjoined to use the utmost vigilance. Nevertheless, the Iroquois war-parties broke in at various points, burning and butchering, and spreading such terror that in some districts the fields were left untilled and the prospects of the harvest ruined. Towards the end of July, Frontenac left Major Prévost to finish the fortifications, and, with the intendant Champigny, went up to Montreal, the chief point of danger. Here he arrived on the thirty-first; and, a few days after, the officer commanding the fort at La Chine sent him a messenger in hot haste with the startling news that Lake St. Louis was "all covered with canoes." [19] Nobody doubted that the Iroquois were upon them again. Cannon were fired to call in the troops from the detached posts; when alarm was suddenly turned to joy by the arrival of other messengers to announce that the new comers were not enemies, but friends. They were the Indians of the upper lakes descending from Michillimackinac to trade at Montreal. Nothing so auspicious had happened since Frontenac's return. The messages he had sent them in the spring by Louvigny and Perrot, reinforced by the news of the victory on the Ottawa and the capture of Schenectady, had had the desired effect; and the Iroquois prisoner whom their missionary had persuaded them to torture had not been sacrificed in vain. Despairing of an English market for their beaver skins, they had come as of old to seek one from the French. [19] "Que le lac estoit tout convert de canots." Frontenac au Ministre, 9 et 12 Nov., 1690.