It was only a thin red line that stretched across the Plains of Abraham. But the Americans dared not face it. The newly arrived ships might, they feared, carry a force up the river and cut off retreat; so, after some desultory skirmishing, the investing army fled. It was now commanded by General Wooster, for Arnold had gone to Montreal. The flight soon became a panic. Arms, clothes, food, private letters and papers were thrown away. Nairne was in command of a portion of the Highland Emigrants, who were the vanguard of the British pursuing force, and was among the first to occupy the American batteries. On that very ground he had fought, victorious in 1759, woefully beaten in 1760; now, a victor again, he helped to drive back a force, some of whose members had been his companions in those earlier campaigns. That night the relieved British slept secure in Quebec, while the bedraggled American force was making its distressful way towards Montreal. Though the American army soon withdrew from Montreal and from Canada, the war was still to drag on for many weary years. Throughout the whole of it Nairne remained on active service. In September, 1776, we find him in command of the garrison at Montreal. In 1777 he was sent to command the post at Isle aux Noix which guarded the route into Canada by way of Lake Champlain. Here Fraser was serving under him as Captain; the two friends were usually together throughout the war. At Isle aux Noix Nairne remained until June, 1779. We get glimpses from his letters of the defects in the service at this time. There were involuntary evils, such as scurvy, caused by want of fresh meat and vegetables, but relieved by drinking a decoction of hemlock spruce. Moral evils there were too, such as gambling and drunkenness; in 1778 the commanding officer gave warning that he had heard of losses at play, and that those taking part in such practises would be excluded from promotion.