General Smithers, the commander of the Southern Confederation militia during the Rocky Mountain War, was ordered by Governor-General Henry Gilpin in March 1850 to lead his men west through the Rocky Mountains in order to relieve the endangered army of General David Homer. However, the order to Smithers was lost in transmission, and Smithers did not learn of it until it had become too late to save Homer's force. Nevertheless, Smithers led his men in a desperate forced march across Mexico del Norte and Arizona in the summer and fall of 1850.In November, Smithers' S.C. militia reached the town of Bald Eagle, Arizona, and spent two days leveling it, before advancing into California and entering the Sierra Nevada Mountains at Williams Pass. Smithers succeeded in trapping a Mexican army led by General Michael Doheny, while Homer's army was trapped between Doheny's army and that of General Francisco Hernandez of the California Brigades. All four armies soon found themselves snowed in, and spent the next five months battling each other for survival. By April 1851, most of the members of all four armies had died of exposure or starvation, including Smithers.
Sobel's source for FitzJohn Smithers' role in the Rocky Mountain War is General Wesley McDougall's The Lessons of the Rocky Mountain War (London, 1914).