He enlisted at Pinckney, Lewis County, New York to serve one year, and was mustered in as a Private in Company G on the same day. Mustered out with his company at Petersburg, Virginia. He was a member of Custer Post No. 6 of Tacoma, Pierce County, Washington.
Aberdeen Herald (4 Jan 1909):
Thomas Armstrong, Well Known Pioneer of Chehalis County, Passes Great Divide. News of the death of Thomas Armstrong, which occurred on Monday December 28, 1908, at his home in Westport, was received in Montesano with deep regret, for here he was well known and highly respected. He had been ailing but a short time, up to Saturday last having enjoyed his usual health. His death was due to heart trouble. He was a native of Flowerbank, Kirkcudbrightshire, Scotland, and was aged 72 years and 7 months. He came to the United States at an early age and served in the War of the Rebellion. In early days he came to Washington, first locating at Tacoma and after wards removing to Montesano, where he lived many years and conducted a hotel. At one time he served the people with credit as a member of the city council. About two years and a half ago he moved to Westport, where he remained until his death. The body was brought to Montesano by steamer on Wednesday and the funeral took place from the Presbyterian church on Thursday afternoon, at 2 o'clock, Rev. R. L. Shelley officiating. The interment was in Wynoochee cemetery and was under the auspices of the local post G.A.R., of which he was a member. Deceased leaves a widow and adopted daughter to mourn his loss and to whom the sympathy of the community is tendered in this their hour of bereavement. – Montesano Vidette.
Find-a-Grave # 175800947