[2] This camp was located on the W. 1/2 of the N.W. 1/4 of section 28, and the E. 1/2 of the N.E. 1/4 of section 29, township 147 north, of range 60 west, on the northeast side of what is now known as Lake Sibley, and about 11 miles in a direct line to the northwest of Cooperstown, Griggs County, North Dakota.--T. H. L.
On the 20th, all the arrangements having been completed, the expedition began a more rapid advance in pursuit of the enemy, and on the 24th of July, 89 miles from Camp Atchison was fought the battle of "Big Hills" or "Big Mound." As soon as it was known that the Indians were in force, the train was corralled on the margin of a small lake, Big Mound being directly to the eastward and distant about one and one-quarter miles. The Sixth Regiment with one company of Mounted Rangers and a section of artillery occupied the east front, and threw up a line of earthworks for protection. As soon as the attack began, Colonel Crooks at once deployed Companies E, I, and K of the Sixth and A of the Ninth, under Major McLaren, as skirmishers, and they pursued the Indians two and one-half miles. Three companies of the Sixth were also deployed on the left flank, and the Indians were repulsed at that point. Major McLaren with companies A, B, D, I, and K advanced four miles at a double-quick, having been ordered to support the troops already at the front, but on their arrival they were ordered to return to camp.
On the 25th the expedition moved only about five miles to a better camping place and remained there on account of the jaded horses. On the 26th, with the Sixth Regiment in advance, the march was resumed. On arriving at Dead Buffalo Lake, some 15 miles from the last camp, the Indians again appeared in force and commenced an attack. Colonel Crooks immediately deployed a part of the Sixth, including Company E, as skirmishers, under Lieutenant Colonel Averill, and they advanced steadily, driving the enemy as they went; the remainder of the regiment under Major McLaren being held in reserve. After an advance of about one and one-half miles Major McLaren with five companies of the Sixth was ordered to return to the camp at the lake, three companies remaining at the front. Desultory firing was kept up until about 3 p.m., when the Indians made a final assault, which was repulsed in fine style by the troops under command of Major McLaren. The Indians, having been defeated at every point, now withdrew from the field.