Milton Jennings Miller was born around 1831 in Springfield, Ohio, to John and Joanna Miller. His father was a farmer who owned $8,000 of real estate by 1850. He lived in Bethel, Ohio, and by 1850, he was also working as a farmer. He enrolled at Antioch College in the early 1850s. By the early 1860s, he was working as a minister in Cambridge, Massachusetts. He married Hannah Dean Allen on September 6, 1863, and the couple apparently had no children.
In August 1864, he became a chaplain in the 110th Ohio Infantry. The regiment took part in the siege of Petersburg, and he mustered out on June 25, 1865. They settled in Geneseo, Illinois, in 1860s, and he continued to work as a minister. By 1870, he owned $800 of real estate and $3,000 of personal property. They employed at least two white servants. By 1900, he was working as a “Capitalist.” He died in 1919.