James LeRoy Davenport was born on January 27, 1845, in Keene, New Hampshire, to Lockhart and Julia Davenport. His father worked in the “lumbering” industry, and he owned $1,500 of real estate and $600 of personal property by 1860. He grew up and attended school in Hinsdale, New Hampshire, and he moved to Beloit, Wisconsin, in the early 1860s.
He enlisted in the Union army on May 23, 1864, and he mustered in as a private in Company B of the 40th Wisconsin Infantry. He mustered out on September 16, 1864.
He settled in Keene, New Hampshire, after leaving the army, and he married Ella Carpenter around 1868. They had at least two children: Mary, born around 1870; and Fannie, born around 1872. He worked as a commercial agent in Keene. He moved to Washington, D.C., around 1881 and took a position as a clerk in the United States Pension Bureau. He received a series of promotions, and in 1909, he became a commissioner. He held the position until 1913, and he died of “carcinoma of [the] bladder” in Falls Church, Virginia, on April 2, 1914.