The following is from the book, Encyclopedia of Indian Wars, by Gregory F. Michno.
26 October 1853: Capt. John W. Gunnison of the U.S. Corps of Topographical Engineers led a 37-man expedition to explore the 38th parallel. Among the members were a topographer, Richard Kern, and a German botanist, Frederick Creuzefeldt. The military escort included a detachment of Company A, Mounted Rifles. The party left Fort Leavenworth, Kansas, on 23 June, surveyed Cochetopa Pass and the San Luis Valley; crossed the San Juan Mountains, the Green River, and the Wasatch Range; and reached the valley of the Sevier River in October.
On 26 October, Gunnison and an advance party of ten men were washing in the river southwest of present-day Delta, Utah, while the others prepared breakfast in camp. A band of Paiutes, or possibly Pahvants (Utes), under the leader Kanosh, struck Gunnison's party from all sides. Gunnison went down, riddled with arrows, as did Creuzefeldt. The soldiers scattered, and the Indians picked them off easily.
In all, seven died, and four escaped. When the main survey party came upon the scene two days later, wild animals had picked clean what the Indians had left behind. Lt. Edward G. Beckwith, 3rd Artillery, took command of the expedition and made winter camp at Salt Lake City.