Early in the year 1865 a military camp was established near the present City of Casper and was known as “Platte Bridge.” Upon the recommendation of Lieut.-Col. W. O. Collins of the Eleventh Ohio Cavalry, it was changed from a small and occasional troop station to a permanent post. In his official communication, Lieutenant Colonel Collins said: “The permanent cure for the hostilities of the northern Indians is to go into the heart of their buffalo country and build and hold forts until the trouble is over.”
On March 28, 1865, the District of the Plains was established by order of Gen. Granville M. Dodge, with Gen. P. E. Connor in command of the new district. Platte Bridge was then made one of the most important posts of the district. Being located as it was, on the North Platte River, 120 miles west of Fort Laramie, it was in the center of the Indian hostilities. Lieut. Caspar Collins, a son of Lieut.-Col. W. O. Collins, had come west with his father in 1862, and when the latter returned east, remained with his company on the plains. An account of his death at Platte Bridge, in the engagement with the Indians on July 26, 1865, is given in the chapter on Early Military History, and on November 21, 1865, Maj.-Gen. John Pope issued the order changing the name of the post to Fort Casper, in his honor. The fort was finally abandoned in 1867.
Source: History of Wyoming, Volume 1, by I. S. Bartlett, Chicago, The S. J. Clarke Publishing Company, 1918