Fort Assiniboine (sic), guardian of Montana's frontier was established by act of Congress in May, 1878. Lt. Colonel Brooks selected this high site on Beaver Creek and superintended the million-dollar construction of the the fort, which took its name from the neighboring Assiniboine (sic) Indians tribe. The infantry and cavalry detachments stationed here to hold off
marauding Indians, including Sitting Bull's hostile Sioux, never actually took part in a single engagement after Fort Assiniboine (sic) was completed. But this new post became one of four important forts nominally guarding the border. General Pershing, then a young lieutenant, served here in the"nineties." After the tenth cavalry was ordered to Cuba in 1898, Fort Assiniboine was practically abandoned, and in 1911 President Taft signed the bill which abolished the largest military reservation in the United States.