Leonidas R. Hollenbeck was born around 1840 in present-day West Virginia to Henry and Margaret Hollenbeck. His father was a farmer who owned $250 of personal property by 1860. They lived in Cabell County, Virginia, until the 1850s, when they moved to Wayne County, Virginia. By 1860, he was working as a farm laborer.
He remained loyal to the Union during the Civil War. He enlisted in the Union army on August 14, 1861, and he mustered in as a private in Company G of the 1st Virginia Cavalry. The regiment was later redesignated the 1st West Virginia Cavalry. It took part in the Battle of Gettysburg and the Shenandoah Valley campaign of 1864. He supported President Abraham Lincoln in the election of 1864. He mustered out on November 21, 1864.
He married Emeline Marks on January 29, 1865, and they had at least seven children: William, born around 1866; Reuben, born around 1868; Grace, born around 1871; Albert, born around 1875; Cora, born around 1879; Nellie, born around 1884; and Edgar, born around 1889. They moved to Loda, Illinois, in the mid-1860s and then to Jackson, Missouri, in the 1870s. He earned a living as a farmer. They moved to Kansas in the early 1880s, and by 1900, they were living in Burdine, Missouri. He died on June 25, 1912.