Nathaniel was born on the 28th of September 1836, in Piermont, New Hampshire, and he enlisted in the 11th New Hampshire Regiment Volunteer Infantry in August of 1862. It was his actions as a Sergeant during the Battle of Spotsylvania, on the 12th of May 1864, that would later earn him the Medal of Honor. The citation reads:

Six color bearers of the regiment having been killed, he voluntarily took both flags of the regiment and carried them through the remainder of the battle.

The following month, Nathaniel was wounded in Cold Harbor, Virginia, and was discharged the following year on the 25th of May. He was married to Weltha Melvin, and the couple had one son, Edgar. Nathaniel received the Medal of Honor on the 23rd of September 1897, in a ceremony at the Massachusetts Association of New Hampshire Veterans. Nathaniel Churchill Barker died on the 7th of March 1904, at the age of 67 in Somerville, Massachusetts, and he is buried with his wife in the Last Rest Cemetery in Merrimack, New Hampshire: Section B, Lot 17.