Previously having achieved the rank of major general of the Union Army during the American Civil War, he had also been awarded the U.S. Medal of Honor for his actions in the First Battle of Bull Run.

He briefly worked for two railroads in eastern Pennsylvania before returning home to Norristown to assist his father in the real estate and stage line businesses.

When their term of enlistment was up, the regiment returned to Pennsylvania, although it was the eve of the First Battle of Bull Run, and firing had already begun.

This act earned him the Medal of Honor on August 21, 1886, for volunteering his services to fellow Pennsylvanian Col. William B. Franklin.

His citation reads: "Voluntarily served as an aide and participated in the battle after expiration of his term of service, distinguishing himself in rallying several regiments which had been thrown into confusion.

In July 1862, Hartranft's men proceeded to Newport News, Virginia, to become part of Burnside's IX Corps, with whom they fought in the Second Battle of Bull Run and at South Mountain.

They also fought at the Battle of Antietam, where Hartranft led the famous charge across Burnside's Bridge, suffering 120 casualties.

[5] He commanded the 1st Brigade, 3rd Division, of the IX Corps in the 1864 Overland Campaign, participating in the fighting at the Wilderness and Spotsylvania.

When the IX Corps was reorganized, Hartranft was given command of a new 3rd Division, consisting of newly raised Pennsylvania regiments.

[5] In the aftermath of the assassination of United States President Abraham Lincoln, Hartranft was appointed both commanding officer of the Old Capitol Prison in Washington, D.C., and as a special provost marshal during the trial of those accused in the Lincoln assassination: George Atzerodt, David Herold, Lewis Paine (also known as Lewis Powell), and Mary Surratt, who would become the first woman to be executed by the U.S. government.

When asked if the convicted had any final statements, the spiritual advisors of Atzerodt and Payne stated that both men wished to thank Hartranft and the officers and soldiers serving under him for the kindness they displayed during their incarceration.

The prisoners were then simultaneously executed by hanging at 1:25 p.m.[7][8] Following the war Hartranft switched party allegiances and became a Republican.

He was a strong advocate of education, municipal reform, regulation of banking, improved industry and commerce, and the reorganization of the National Guard.

He supported suffrage for African Americans, fought the corrupt Simon Cameron political machine, and championed the rights of the workingman.

At the Republican National Convention in June 1876, he was a contender for the presidential nomination, but Rutherford B. Hayes of Ohio was eventually selected.

Concerned with the governor's precedent in calling out the militia to battle civilians in Pittsburgh, the District Attorney of Allegheny County tried to force Hartranft to appear before a grand jury to explain his rationale.

Citation: Voluntarily served as an aide and participated in the battle after expiration of his term of service, distinguishing himself in rallying several regiments which had been thrown into confusion.