While, however, the intervention of France greatly increased the difficulties with which Great Britain had to contend at this critical time of her history, for the moment it made the war more popular in England, inasmuch as Englishmen were now called upon to fight against their old rivals and not merely against their kinsfolk. In another respect too it was of distinct advantage to the British Empire, in that it brought to Canada immunity from invasion. The American colonists welcomed French aid in securing their independence, but they had no mind to restore Canada to France, and they looked with suspicion on any proposal or utterance which might seem to point in that direction. Though the French in their treaty with the United States disclaimed any intention of national aggrandizement in America,[149] Admiral D’Estaing, in October, 1778, a few months after his arrival in American waters, issued a proclamation to the Canadians, appealing to their French nationality; and Lafayette proposed a scheme for an invasion of Canada which Congress accepted but Washington set aside. There was sufficient uneasiness in American minds with regard to French designs to restrict French co-operation in the main to the Atlantic side; and, though the Canadians were excited by their countrymen’s appeal, they did not rise in arms themselves, nor did the Americans attempt to repeat the movement by which Montgomery had over-run the country up to the walls of Quebec. [Sidenote: Precautions taken in Canada against invasion.] It would not indeed have been easy for them to do so, for Carleton and his successor Haldimand, though badly in need of reinforcements, were yet better prepared and had more men at their command than when the war first broke out. Immediately after Burgoyne’s capitulation Ticonderoga and Crown Point were abandoned, and the troops were withdrawn to the northern end of Lake Champlain. A year later Haldimand directed the whole country round the lake to be cleared of settlement and cultivation, as a safeguard against American invasion. At various points, where such invasion might take place, he established posts, on an island at the opening of Lake Ontario, which was named Carleton Island; at the Isle aux Noix at the head of the Richelieu river, and at Sorel at its mouth: on the river St. Francis which joins the St. Lawrence below Sorel, flowing from the direction of Vermont: and on the Chaudière river over against Quebec, lest Arnold’s inroad by the line of that river should be repeated. [Sidenote: Border War.]