Montgomery was born in Ashtabula County, Ohio on December 22, 1814. He received an academic education and in 1837 went to Kentucky, where he was for a time engaged in teaching school. While there, he joined the Christian Church and became a minister, but later in life espoused the doctrines of the Adventists.
In 1852 he moved to Pike County, Missouri with his family, and a year later he went to Jackson County, in order to be ready to enter Kansas as soon as the territory was organized and the lands opened to settlement. Some of his friends, among whom was Dr. Thornton, knowing him to be opposed to slavery, persuaded him to go to Bates County, Missouri, by telling him that he could obtain as good land there as he could in Kansas. He accepted their advice, but quickly became dissatisfied in Bates County and returned to his original resolution to settle in Kansas.
Accordingly, he purchased a claim from a pro-slavery settler about five miles from the present town of Mound City late in the year 1854. It was not long until he was recognized as a leader by the Free-State men of what would become Linn County. In 1857 he organized and commanded the “Self-Protective Company,” which had been formed to defend the rights of the anti-slavery settlers, and backed by this organization, Montgomery ordered some of the most ardent pro-slavery citizens to leave the territory.
After their departure, he settled down to improve his claim, but later that year some of the Free-State men of Bourbon County, who had been expelled by George W. Clarke in 1856, returned to take possession of their homes along the Little Osage River. They met with opposition and called upon Montgomery for assistance. In December he took the field with his company and created so much disturbance that Governor James Denver found it necessary to order a detachment of soldiers to that part of the state to preserve order.
During the border troubles preceding the Civil War, some of his men would frequently indulge in plundering their enemies, but Montgomery was never a party to such proceedings.
In 1859 he was a candidate for representative in the Kansas Territorial Legislature but was defeated by W. R. Wagstaff. When the Civil War began, he was mustered into the Union Army as a colonel of the Third Kansas Infantry on July 24, 1861. He was soon transferred to the command of the Second South Carolina Colored Regiment, with which he made a raid into Georgia. This regiment distinguished itself at the Battle of Olustee, Florida on February 20, 1864.
After the war, he returned to his home in Linn County, Kansas, where he died on December 6, 1871.
“He died poor, although he had abundant opportunity to steal himself rich in the name of liberty.”