The dense forests which covered the country between the hostile armies concealed their movements, and as Gates threw out no harassing parties, his information concerning the enemy was vague. Burgoyne, however, was diligently collecting all his forces from Skenesborough, Fort Anne and Fort George, and collecting provisions. So stood matters on the 11th of September, when a report was circulated in the American camp that Burgoyne was in motion, and that he had made a speech to his soldiers, telling them that the fleet had returned to Canada, and their only safety was to fight their way to New York.
As General Gates was to receive an attack, it was thought he ought to choose the ground where to receive it. Arnold, therefore, in company with Kosciuszko, the Polish engineer, reconnoitred the neighborhood in quest of a good camping-ground, and at length fixed upon a ridge of hills called Bemis's Heights, which Kosciuszko proceeded to fortify. In the meantime Colonel Colburn was sent off with a small party to ascend the high hills on the east side of the Hudson, and watch the movements of the enemy with glasses from their summits, or from the tops of the trees. For three days he kept thus on the look-out, sending word from time to time to camp of all that he espied.
On the 11th there were the first signs of movement among Burgoyne's troops. On the 13th and 14th they slowly passed over a bridge of boats, which they had thrown across the Hudson, and encamped near Fish Creek. On the 15th, both English and Hessian camps struck their tents, and loaded their baggage wagons. By twelve o'clock both began to march. Colburn neglected to notice the route taken by the Hessians; his attention was absorbed by the British, who made their way slowly and laboriously down the western side of the river, along a wretched road intersected by brooks and rivulets, the bridges over which Schuyler had broken down. The division had with it eighty-five baggage wagons and a great train of artillery; with two unwieldy twenty-four-pounders, acting like drag anchors. Having seen the army advance two miles on its march, Colburn descended from the heights, and hastened to the American camp to make his report. A British prisoner, brought in soon afterwards, stated that Burgoyne had come to a halt about four miles distant.
On the following morning the army was under arms at daylight; the enemy, however, remained encamped, repairing bridges in front, and sending down guard-boats to reconnoitre. The Americans, therefore, went on to fortify their position. The ridge of hills called Bemis's Heights, rises abruptly from the narrow flat bordering the west side of the river. Kosciuszko had fortified the camp with intrenchments three-quarters of a mile in extent, having redoubts and batteries, which commanded the valley and even the hills on the opposite side of the river, for the Hudson, in this upper part, is comparatively a narrow stream. From the foot of the height an intrenchment extended to the river, ending with a battery at the water edge, commanding a floating bridge.
The right wing of the army, under the immediate command of Gates, and composed of Glover's, Nixon's, and Patterson's brigades, occupied the brow of the hill nearest to the river, with the flats below. The left wing, commanded by Arnold, was on the side of the camp farthest from the river, and distant from the latter about three-quarters of a mile. It was composed of the New Hampshire brigade of General Poor, Pierre Van Courtlandt's and James Livingston's regiments of New York militia, the Connecticut militia, Morgan's riflemen, and Dearborn's infantry. The centre was composed of Massachusetts and New York troops.
Burgoyne gradually drew nearer to the camp, throwing out large parties of pioneers and workmen. The Americans disputed every step. A Hessian officer observes: "The enemy bristled up his hair, as we attempted to repair more bridges. At last we had to do him the honor of sending out whole regiments to protect our workmen."
Burgoyne now encamped about two miles from General Gates, disposing his army in two lines; the left on the river, the right extending at right angles to it, about six hundred yards across the low grounds to a range of steep and rocky hills, occupied by the élite; a ravine formed by a rivulet from the hills passed in front of the camp. The low ground between the armies was cultivated; the hills were covered with woods, excepting three or four small openings and deserted farms. Beside the ravines which fronted each camp, there was a third one, midway between them, also at right angles to the river.
On the morning of the 19th, General Gates received intelligence that the enemy were advancing in great force on his left. It was in fact their right wing, composed of the British line and led by Burgoyne in person. It was covered by the grenadiers and light-infantry under General Fraser and Colonel Breyman, who kept along the high grounds on the right; while they, in turn, were covered in front and on the flanks by Indians, provincial royalists and Canadians. The left wing and artillery were advancing at the same time, under Major-general Phillips and Riedesel, along the great road and meadows by the river side, but they were retarded by the necessity of repairing broken bridges. It was the plan of Burgoyne that the Canadians and Indians should attack the central outposts of the Americans, and draw their attention in that direction, while he and Fraser, making a circuit through the woods, should join forces and fall upon the rear of the American camp. As the dense forests hid them from each other, signal guns were to regulate their movements. Three, fired in succession, were to denote that all was ready, and be the signal for an attack in front, flank and rear.
The American pickets, stationed along the ravine of Mill Creek, sent repeated accounts to General Gates of the movements of the enemy; but he remained quiet in his camp as if determined to await an attack. The American officers grew impatient. Arnold especially, impetuous by nature, urged repeatedly that a detachment should be sent forth to check the enemy in their advance, and drive the Indians out of the woods. At length he succeeded in getting permission, about noon, to detach Morgan with his riflemen and Dearborn with his infantry from his division. They soon fell in with the Canadians and Indians, which formed the advance guard of the enemy's right, and attacking them with spirit, drove them in, or rather dispersed them. Morgan's riflemen, following up their advantage with too much eagerness, became likewise scattered, and a strong reinforcement of royalists arriving on the scene of action, the Americans, in their turn, were obliged to give way.
Other detachments now arrived from the American camp, led by Arnold, who attacked Fraser on his right, to check his attempt to get in the rear of the camp. Finding the position of Fraser too strong to be forced, he sent to head-quarters for reinforcements, but they were refused by Gates, who declared that no more should go. The reason he gave was that it might be attacked by the enemy's left wing. Arnold now made a rapid countermarch, and his movement being masked by the woods, suddenly attempted to turn Fraser's left. Here he came in full conflict with the British line, and threw himself upon it with a boldness and impetuosity that for a time threatened to break it, and cut the wings of the army asunder. The grenadiers and Breyman's riflemen hastened to its support. General Phillips broke his way through the woods with four pieces of artillery, and Riedesel came on with his heavy dragoons. Reinforcements came likewise to Arnold's assistance; his force, however, never exceeded three thousand men, and with these, for nearly four hours, he kept up a conflict almost hand to hand, with the whole right wing of the British army.