Daniel R. Hillard was the son of Nancy Jane McMillan (1808-1885) and John Hillard (1793-1851).

Late in the Civil War, he was drafted and then assigned to Company C, 53rd. Regiment of the Pennsylvania Volunteers on November 16, 1864 with the rank of Private. During his enlistment, the 53rd participated, on the front lines, in the siege of Petersburg, during the winter of 1864 and spring of 1865. They participated in the battle of Boydton Plank Road, and at Five Forks. The 53d assisted in the capture of the enemy's wagon trains at Sailor's Creek and was at the front near Appomattox Courthouse on the day of General Robert E. Lee's surrender. He later marched in the Grand Review of the Armies in Washington, D.C. on May 23, 1865 and was mustered out near Alexandria, Virginia on June 30, 1865, having served seven months and sixteen days. The 1890 Veterans Census Schedule shows his disability as "Chronic Diarrhea, not able to work half of the time".

He married Jennie Rose Rodgers (1856-1940) on February 23, 1882 in Butler County, Pennsylvania.
Adopted son:
• Karl Alton Sibbalds Hillard (1883-1944)

The following excerpt is from the "20th. Century History of Butler County" edited and compiled by James A. McKee, Butler, PA, published by Richmond-Arnold Company, Chicago, Illinois in 1909:

"Daniel R. Hillard was reared on the home farm with his brothers and sisters and with them attended the Blair and the Campbell schools in Venango Township. He continued to live at home and he received about forty acres of the homestead from his brother James, by will, and to this he added thirty-five acres by purchase. The farm is well improved and Mr. Hillard assisted in putting up the present substantial farm buildings, which make this a comfortable and attractive home. There are two fine orchards on the place, one of them having been set out by his grandfather."

Obituary, Butler Citizen, Feb 10, 1915:

Daniel R. Hilliard, aged 71 years, a lifelong resident of Venango township, died at his home there Thursday morning, February 4, from hardening of the arteries. Mr. Hilliard was a survivor of the Civil War, having been a member of the Fifty-third regiment, Pennsylvania Volunteers. He was a member of the G.A.R. His wife and one brother, Jonathan B. Hilliard survive.
Funeral services were held Saturday morning at 11 o'clock at the Eau Claire United Presbyterian church by Rev. W. R. Skinner. Interment was made in the Eau Claire cemetery.