Millar's birth in Front Royal came about when his parents were visting from Davenport, Iowa. His father died when he was only four years old, and he and his mother returned to Front Royal to live with his aunt, Mrs. William Richardson, at Rose Hill, the family home. He received his primary education at the Front Royal Academy, then attended Griswold College in Davenport. In 1876 he went to the University of Heidelburg, Germany, where he studied Consitutional and International Law, Economics and History, receiving a PhD. in 1880. From there he continuted his education at the University of Berlin, where he continued his studies in Economics and History. While in Germany, his mother, Susan, died. He returned to Front Royal with her remains which were placed in a vault in the family cemetery.

On October 3, 1882, Dr. Millar married Bertha Reidel, of Heidelburg, who was visiting her uncle in Brooklyn, NY. To this marriage five children were born. They were Susan Bertha millar, Elizabeth Ann Millar, Florence Virginia Millar, Samuel Rolfe Millar, Jr., and Bertha Randolph Millar.

Samuel and his wife lived in Front Royal at first, but some property concerns in Iowa brought them back to Davenport. For a year he was connected with the davenport Gazette as Assistant Editor and president of the company publishing the paper. He traveled to Germany with his wife and baby Susan and in March 1886 was appointed U.S. Consul in Leiprig, by President Grover Cleveland. He held this post until Celveland's term ran out in 1889. The Millars returned to Virginia and lived in Charlottesville for three years where he lectured on Economics at the University of Virginia. He also lectured at Washington and Lee University. After a visit to Germany he returned to Front Royal in 1894 when he began construction on "Mountain View" [destroyed by fire in 1985] on the old Millar estate.

In the year 1900, Millar and Professor J.S. Grurer founded Eastern College in Front Royal, which, he wrote, "has been in every respect remarkably successful." Samuel Millar did not believe in the conferring of honorary degrees by colleges and refused two that were offered him. He purchased a part interest in the Warren County Sentinel in 1882, and after the death of the Editor, in 1900 he became Editor and remained at this post until his death on February 13, 1930.

He is buried in a tomb at the family cemetery, now located across from the Middle School of Randolph Macon Academy.
Samuel Rolfe Millar is an excellent example of the citizen soldier who is called to active duty when his country has need of him. Most of his military duty was with the Virginia National Guard. He began his military service with the Warren light infantry, 2nd Virginia volunteers as a private in 1882. By 1903 he was a captain of the same company, and by 1905 was a major in the 2nd Virginia volunteers. During W.W.I he served with the 29th "Blue and Gray" Division of the United States Army and retired as a Colonel in September, 1918.

The Colonel's active military campaigns included Federal Service on the Mexican Border from July 1916 to march 1917; and again in Federal Service in the First World War as Lt. Colonel of the 116th Infantry. He was slated for foreign service with the Intelligence section of the General staff a few days before the Armistice was signed.