He was too far removed from the inhabited country to hope for support, and was too weak to maintain Kaskaskia and the Illinois against the combined force of regulars and Indians by which he was to be attacked so soon as the season for action should arrive. While employed in preparing for his defence, he received unquestionable information that Hamilton had detached his Indians on an expedition against the frontiers, reserving at the post he occupied only about eighty regulars, with three pieces of cannon and some swivels. 1779 February.Clarke instantly resolved to seize this favourable moment. After detaching a small galley up the Wabash with orders to take her station a few miles below Vincennes, and to permit nothing to pass her, he marched in the depth of winter with one hundred and thirty men, the whole force he could collect, across the country from Kaskaskia to Vincennes. This march, through the woods, and over high waters, required sixteen days, five of which were employed in crossing the drowned lands of the Wabash. The troops were under the necessity of wading five miles in water, frequently up to their breasts. After subduing these difficulties, Colonel Clarke surprises St. Vincents, and takes possession of it.this small party appeared before the town, which was completely surprised, and readily consented to change its master. Hamilton, after defending the fort a short time, surrendered himself and his garrison prisoners of war. With a few of his immediate agents and counsellors, who had been instrumental in the savage barbarities he had encouraged, he was, by order of the executive of Virginia, put in irons, and confined in a jail.
This expedition was important in its consequences. It disconcerted a plan which threatened destruction to the whole country west of the Alleghany mountains; detached from the British interest many of those numerous tribes of Indians south of the waters immediately communicating with the great lakes; and had, most probably, considerable influence in fixing the western boundary of the United States.
We have already seen that congress, actuated by their wishes rather than governed by a temperate calculation of the means in their possession, had, in the preceding winter, planned a second invasion of Canada, to be conducted by the Marquis de Lafayette; and that, as the generals only were got in readiness for this expedition, it was necessarily laid aside. The design, however, seems to have been suspended, not abandoned. The alliance with France revived the latent wish to annex that extensive territory to the United States. That favourite subject was resumed; Congress determine to attack Canada, and the other British possessions in North America.and, towards autumn, a plan was completely digested for a combined attack to be made by the allies on all the British dominions on the continent, and on the adjacent islands of Cape Breton and Newfoundland. This plan was matured about the time the Marquis de Lafayette obtained leave to return to his own country, and was ordered to be transmitted by that nobleman to Doctor Franklin, the minister of the United States at the court of Versailles, with instructions to induce, if possible, the French cabinet to accede to it. Some communications respecting this subject were also made to the Marquis, on whose influence in securing its adoption by his own government, much reliance was placed; and, in October, 1778, it was, for the first time, transmitted to General Washington, with a request that he would inclose it by the Marquis, with his observations on it, to Doctor Franklin.
This very extensive plan of military operations for the ensuing campaign, prepared entirely in the cabinet, without consulting, so far as is known, a single military man, consisted of many parts.
Two detachments, amounting, each, to sixteen hundred men, were to march from Pittsburg and Wyoming against Detroit, and Niagara.
A third body of troops, which was to be stationed on the Mohawk during the winter, and to be powerfully reinforced in the spring, was to seize Oswego, and to secure the navigation of Lake Ontario with vessels to be constructed of materials to be procured in the winter.
A fourth corps was to penetrate into Canada by the St. Francis, and to reduce Montreal, and the posts on Lake Champlain, while a fifth should guard against troops from Quebec.
Thus far America could proceed unaided by her ally. But, Upper Canada being reduced, another campaign would still be necessary for the reduction of Quebec. This circumstance would require that the army should pass the winter in Canada, and, in the mean time, the garrison of Quebec might be largely reinforced. It was therefore essential to the complete success of the enterprise, that France should be induced to take a part in it.
The conquest of Quebec, and of Halifax, was supposed to be an object of so much importance to France as well as to the United States, that her aid might be confidently expected.
It was proposed to request his Most Christian Majesty to furnish four or five thousand troops, to sail from Brest, the beginning of May, under convoy of four ships of the line and four frigates; the troops to be clad as if for service in the West Indies, and thick clothes to be sent after them in August. A large American detachment was to act with this French army; and it was supposed that Quebec and Halifax might be reduced by the beginning or middle of October. The army might then either proceed immediately against Newfoundland, or remain in garrison until the spring, when the conquest of that place might be accomplished.