Robert S. Stedman was born around 1844 in Utica, New York, to Robert Stedman. His father was a stage driver who owned $200 of personal property by 1860. Stedman grew up and attended school in New York City, and by the early 1860s, he was working as a silver plater.
He enlisted in the Union army on August 12, 1861, and he mustered in as a private in Company C of the 3rd Maryland Infantry. He apparently died about his age, claiming that he was born around 1838. The regiment took part in the Battle of Antietam, the Battle of Chancellorsville, the Battle of Gettysburg, the Overland Campaign, and the siege of Petersburg. He was promoted to corporal in October 1861, to sergeant in January 1862, and to 1st lieutenant in January 1864. In June 1864, he became acting quartermaster for the regiment. He expressed devotion to the Union. In July 1863, he declared that he and his comrades were fighting to "restore the Union to its former place among Nations." Then, in January 1864, he wrote that the "Stars & Stripes...shall never be trampled in the dust while Bob has an arm to defend them."
He supported Abraham Lincoln in the presidential election of 1864, writing that “nothing could have pleased me so much as…Uncle Abes victory did.” Lincoln’s victory, he wrote, proved that “the people of the North are still true to the Union.” When he heard rumors that Confederates “want to negotiate for a peace,” he declared that “this war has been carried on to such an extent that the only terms we can allow are unconditional surrender.” He mustered out on July 31, 1865.
Stedman settled in New York City after the war and resumed his work as a silver plater. He married Hester Beaver, and they had at least six children: Ida, born around 1867; Estella, born around 1869; Ella, born around 1871; Josephine, born around 1873; Gertrude, born around 1875; and Albert, born around 1877. The family moved to Hackensack, New Jersey, in the late 1800s. He applied for a federal pension in October 1890 and apparently received one. He died in Hackensack on October 10, 1898.