Julius Hayden was born on September 18, 1838, in Candor, Pennsylvania, to Sidney Hayden and Florilla Miller. His father was a farmer and brick maker who owned at least $10,000 in real estate by 1850. Hayden attended school in Athens, Pennsylvania, and by 1860, he was working as a railroad agent. During the Civil War, he worked for the United States Military Railroad, an agency that operated rail lines seized by the federal government. Hayden was stationed in Alexandria, Virginia, during the summer of 1864, and the government transferred him to Tennessee that November.
Hayden married Estelle Whitaker in the mid-1860s, and they had at least three children together: Algernon, born around 1867; Leslie, born around 1869; and Bert, born around 1874. He continued working for the railroad industry after the war, moving from Pennsylvania to Louisiana to New York. He moved to Jacksonville, Florida, around 1885 and became superintendent of the Jacksonville and Atlantic Railroad. He finally retired in the fall of 1893, and he died in Jacksonville on February 22, 1894.