John Otto was born in 1835 in Germany.
In 1860 there was a John Otto reportedly living in Clinton Township, Macomb County. In any case John immigrated to North America and had settled in eastern Michigan by the winter of 1863.
John stood 5’5” with blue eyes, light hair and a dark complexion and was a 28-year-old carpenter, possibly living in Macomb County when he became a substitute for Frederick Kaufman, who had been drafted on February 17, 1863, for 9 months from Erin, Macomb County. John enlisted in February of 1863 in Unassigned at Erin, for 3 years, crediting Erin, and was sent to the Regiment on March 6.
There is no further record. No pension seems to be available.
(There was one John Otto, age 40, who enlisted as a Private and substitute in Company K, Fifth New Hampshire infantry on August 8, 1864. He was mustered out on June 28, 1865.)
In 1870 there was a John Otto, born 1835 in Prussia, working as a farm laborer in Warren, Macomb County. He was married to Mary (b. 1832 in Prussia) and they had at least three children: Helena (b. 1855), John (b. 1858) and Mary (1868). They had settled in Michigan sometime before 1855.