Nathaniel Williams Brown was born on February 22, 1811, in Dighton, Massachusetts, to Isaac Brown. his father worked as a merchant. He grew up and attended school in Providence, Rhode Island. One biographer describes him as a "very bright, intelligent boy...distinguished for a wonderfully retentive memory." At the age of 11, however, he developed "inflammation of the eyes," which prevented him from reading for three years. For the rest of his life, he suffered from "acute nervous and inflammatory disease." Unable to attend school, he began working with his father in the wool industry.
He married Sophia S. Frothingham on June 5, 1834, and they had at least three children: Sophia, born around 1837; Lucy, born around 1842; and Langdon, born around 1850. He returned to Dighton in the 1850s, and he worked as a manufacturer. By 1860, he owned $1,400 of real estate.
In the spring of 1861, he received a commission as a captain in Company D of the 1st Rhode Island Infantry. The regiment took part in the First Battle of Manassas, and he reportedly "greatly distinguished himself for coolness and courage" during the battle. He mustered out in August 1861 and returned to Dighton.
He returned to the Union army soon afterward, mustering in as a colonel in the 3rd Rhode Island Heavy Artillery. The regiment was stationed in South Carolina. According to an early biographer, he “manifested all the high and soldierly qualities of a patriot and officer. He was a wise and thorough disciplinarian, prompt and unwavering in action, and ever watchful and considerate in the interests of his regiment.” He contracted a “virulent fever” on October 25, 1862, and he died in Hilton Head, South Carolina, five days later.