Angus (August) McIntosh was born around 1837 in Scotland. He immigrated to America around 1855 settled in Bergen, New York. By 1860, he was working as a farmer, and he owned $2,000 of real estate and $550 of personal property.
He enlisted in the Union army on August 17, 1862, and he mustered in as a private in the 9th New York Heavy Artillery on October 28. He eventually earned a promotion to corporal. The regiment took part in the Overland Campaign and the siege of Petersburg. He was probably wounded sometime during the war. Union forces transferred him to the 2nd New York Heavy Artillery in June 1865, and he mustered out on July 24, 1865.
He settled in Riga, New York, after the war and resumed his work as a farmer. He married Laura Gordon, and they had at least two children: Fred, born around 1877; and Blanch, born around 1879. His wife died in 1882, and he married a woman named Ella around 1885. They had at least three children: Lula, born around 1882; George, born around 1889; and Alexander, born around 1890. By 1890, he was suffering from kidney disease. His wife died in 1905, and he remained in Riga with his children. He died in Churchville, New York, on April 29, 1919.