Robert N. Harding was born around 1827 in Indiana to Samuel and Jane Harding. His father was a farmer who owned $15,000 of real estate and $1,000 of personal property by 1860. The family lived in Wayne, Indiana, and by 1850, he was also working as a farmer.
He enlisted in the Union army on December 9, 1861, and he mustered in as a sergeant in Company G of the 47th Indiana Infantry. The regiment took part in the siege of Vicksburg and the Red River campaign. He was promoted to 2nd lieutenant in February 1863, and he mustered out on October 23, 1865.
He returned to Wayne after the war and resumed his work as a farmer. He married Nancy Smith on May 16, 1865, and they had at least two children: Eugene, born around 1868; and Robert, born around 1873. By 1870, he owned $2,500 of personal property. He also served as deputy sheriff. He supported the Republican Party, and he attended several local conventions in the 1880s. His wife died in the late 1800s. In 1900, he briefly served as superintendent of the Marion County Workhouse. He died of pulmonary tuberculosis on November 2, 1903, in the Central Indiana Hospital for the Insane.