For some years the Indians who were parties to the treaty of Laramie observed its conditions fairly well; but in 1854 an unfortunate affair occurred which temporarily interrupted the general peace. Some fifteen hundred Indians of three different Sioux bands were encamped in the Platte Valley, about six miles below Fort Laramie, in August of that year. One of the Indians drove off and killed a stray cow belonging to an emigrant train. The owner complained of the theft to the officer in command at Laramie, and Lieutenant Grattan, with about twenty men, was sent to bring in the thief. He probably did not show very much tact in performing his delicate task, and made the mistake of attempting to take the culprit by force in the presence of nearly ten times his number of Indians. The result was the massacre of his entire party. The Indians then went to the American Fur Company warehouse, where their annuity goods were in waiting, broke open the building, and carried off the annuities. [Sidenote: BATTLE OF ASH HOLLOW.] Thereupon the government ordered General Harney to take the field with a military force, establish convenient bases of supplies, protect the frontier and the emigrant routes, and to deal a heavy blow upon the offending Indians. On September 3, 1855, General Harney attacked a large force of Indians who had taken part in the Grattan massacre, completely routed them, killed and captured upward of two hundred, and destroyed nearly all their property. This affair took place across the Platte River from Ash Hollow, a noted situation on the emigrant trail, from which the battle has taken its name. General Harney next moved his force to the Missouri River, where the old trading post of Fort Pierre had been lately acquired by the government, and there held councils with various tribes, which again resulted in general pacification. In the following year the important military post of Fort Randall was built, and Fort Pierre was abandoned because of its undesirable situation. General Harney discharged his task in a manner highly creditable to himself and satisfactory both to the Indians and the government; and seven years were to elapse before any further difficulty of a serious character should occur. [Sidenote: SITUATION GROWING WORSE.] [Sidenote: INTRIGUES OF THE HALF-BREEDS.]