Overview: The fight was for the continent. The strategy embraced the lines from Boston to the mouth of the Chesapeake, from Montreal even to Charleston. Montgomery's invasion of Canada, although St. John's and Montreal were taken, failed before Quebec, and the retreat of the American forces gave Burgoyne the base for his comprehensive campaign. Howe had been compelled to give up New England, which contained nearly one-third of the population and strength of the colonies. The center of attack and of defense was the line of New York and Philadelphia. From their foothold at New York, on the one hand, and Montreal on the other, the British commanders aimed to grind the patriots of the Mohawk valley between the upper and nether mill stones. The design was to cut New England off from the other States, and to seize the country between the Hudson and Lake Ontario as the vantage ground for sweeping and decisive operations. This was the purpose of the wedge which Burgoyne south to drive through the heart of the Union. In the beginning of that fateful August, Howe held all the country about New York, including the islands, and the Hudson up to Peekskill; the British forces also commanded the St. Lawrence and Lake Ontario, and their southern shores, finding no opposition north of the Mohawk and Saratoga lake. The junction of Howe and Burgoyne would have rendered their armies masters of the key to the military position. This strip of country from the Highlands of the Hudson to the head of the Mohawk was the sole shield against such concentration of British power. Once lost it would become a sword to cut the patriots into fragments. They possessed it by no certain tenure. Two months later Governor Clinton and General Putnam lost their positions on the Hudson. Thus far Burgoyne's march had been one of conquest. His capture of Ticonderoga had startled the land. The frontier fort at the head of the Mohawk was to cost him the column on whose march he counted so much.