He served in the Union army. I have not been able to locate either a veteran's or widow's application for pensions.
Benjamin H. Bristow
Residence was not listed;
Enlisted on 9/20/1861 at Calhoon, KY as a Lieut Colonel.
On 1/1/1862 he was commissioned into Field & Staff KY 25th Infantry, U. S. A.
He Resigned on 4/15/1862
On 9/8/1862 he was commissioned into Field & Staff KY 8th Cavalry, U. S. A.
He was Mustered Out on 9/23/1863 at Russellville, KY
Promotions:
* Colonel 4/1/1863
Sources used by Historical Data Systems, Inc.:
- Report of the Adjutant General of the State of Kentucky
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Benjamin H. Bristow, age 29, Lieut. Colonel, Field & Staff, 25th Kentucky Infantry, joined for duty and enrolled September 20, 1861 at Hopkinsville for 3 years, wounded April 6-7, 1862 at Pittsburg Landing, Tenn., Knocked from his horse by a shell, resigned April 15, 1862
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Benjamin H. Bristow, age 30, Lieut. Colonel, Field & Staff, 8th Regiment Kentucky Cavalry, joined for duty and enrolled June 25, 1862 at Louisville for 12 months, promoted Colonel April 1, 1863, recorded the end of April, 1863 as Absent on Military Comm. at Louisville as Judge Advocate, last recorded present on the July/August, 1863 muster roll, no further records
M397: Compiled Service Records of Volunteer Union Soldiers Who Served in Organizations from the State of Kentucky
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See: https://www.familysearch.org/learn/wiki/en/8th_Regiment,_Kentucky_Cavalry_(Union)