James Calvin Sly
James C. Sly (August 8, 1807 – August 31, 1864) was a Mormon pioneer, member of the Mormon Battalion in the Mexican-American War, scout for early west trails used during the California gold rush, journal keeper in 1848 and 1849, early US western settler of several communities, and Mormon missionary to Canada.
Service in the Mormon Battalion
1848, A number of brethren who had served in the Mormon Battalion were still working in California, but they were anxious to proceed to the Valley of the Great Salt Lake as soon as a pass should open. According to a previous arrangement a Company of 8 persons started 1 May 1848, Sgt. David Brewett being elected Captain, to pioneer, if possible, a wagon road of the Sierra, Nevada mountains eastward. The Truckee route being impractical at that season of the year.
This company consisted of David Brewett, Captain Ira J. Willis, James C. Sly, Israel Evens, Jacob G. Truman, Esra Allen, J. R. Allred, Henderson Cox and Robert Pixton.
Three days travel brought this Company to Iron Hill where they found snow so deep they could travel no further, a donkey belonging to one of the men was completely buried in the snow except his ears. On this occasion, these appendages were not to be despised, ugly and unique as they usually appear. For one of the men got hold of them and dragged Mr. Donkey out and saved his life. None of that Company will be very likely to wonder why those animals are made with large ears.
Brothers Willis, Sly and Evens ascended to the summit of the mountain seeing nothing but snow-capped mountains in advance of them. It was decided not to abandon but to postpone the enterprise until a later period. So far as they could judge a wagon road would at least be possible and perhaps a success. One days' travel in descending took them back from winters cold snow regions to a warm spring atmosphere where flowers bloomed and vegetation was far advanced. (J of H 1 May 1848).
1848, May 1, a number of Battalion brethren and others in Sacramento Valley, California subscribed $512.00 and bought two brass cannons off Captain John A. Sutter to be taken to Great Salt Lake for the benefit of The Church of Jesus Christ of Latter-day Saints (LDS Church). (Names and amounts listed.) James C. Sly subscribed $10.00. 
J. C. SLY (Tyler’s list, JAMES CALVIN SLY) Private. Mustered out with Company July 16, 1847, at Los Angeles, Cal. ‘By the 2nd of July the company was again on the march. Two days’ travel from Pleasant Valley, that is about fifty miles east of Sutter’s Fort, brought them to Sly’s Park, a small valley or mountain dell, thus named for Captain JAMES C. SLY, who first discovered it…. Four days’ travel over rough and rugged mountains took them across the summit, and they found themselves safely landed at the head of Carson Valley, Nevada.’ 
He married Susannah Gustin on March 25, 1849 in Salt Lake City, Utah.
Sly was accidentally wounded outside Fort Levan early in the Utah Black Hawk War.
- Mormon Battalion Company B
- THE MORMON BATTALION, U. S. ARMY OF THE WEST by Norma Baldwin, Chapter 10, page 205
- Journal of History, (Salt Lake:LDS Church) 1 May 1848.
- “Mormon Battalion,’ Historical record, Vol. VIII page 935
- James C. Sly Diary; SLC Archives & old church records;
- Thomas Gustin bible. J.C. buried in Chicken Creek, but town is gone and the area is covered in farms. Grave unknown...Nephi, Utah records.
- James C. md 1)Mary Bassett 25 Mar 1829, Manchester, NY. Had son, Neamiah b 19 Nov 1829, d 25 Aug 1830. Mary d 25 July 1830...
- James C. md 2) Margriet Jane Fuller 1 Sep 1831. Nancy md Mr. Agers 1869; Curlis Appleby 1872.
- James was in Mormon Battalion and named SLY PARK in California; and was there where Gold was discovered and help found Mormon Trail over the Sierra Mountains. See History by Lenore Sly Waite..Salt Lake Archives.
|Wikimedia Commons has media related to James Calvin Sly.|
- Traveling the Mormon Emigrant Trail (They named this encampment after James C. Sly)
- James Calvin Sly Museum (In the Sly Park Recreation Area) Pollock Pines, California
- Sly's Park, a small valley or mountain dell, thus named for Captain James C. Sly
- Led first wagons on Salt Lake cutoff, became the Gold Rush Trail
- Mormon Battalion Company B Roster
- Time Line of the life of James C. Sly
- Black Hawk Indian War of Utah
- The Pollock Pines Epic
- Scanned Journal Pages