Bingham enlisted in the Union Army and received a commission as a first lieutenant in the 140th Pennsylvania Volunteer Infantry on August 22, 1862. During the Battle of Gettysburg on July 1–3, 1863, he was serving as Captain and Judge-Advocate on the staff of Major General Winfield Scott Hancock's II Corps. During the battle he witnessed Pickett's Charge, and was near the "Angle" where the Confederates reached the "High Water Mark". He received the personal effects from the mortally wounded ConfederateBrigadier General Lewis A. Armistead and carried the news to General Hancock, Armistead's friend from before the war. Bingham was a Mason, and the story of how he provided assistance to the dying fellow Mason, General Armistead, was used in Masonic literature, and commemorated with the Friend to Friend Masonic Memorial at Gettysburg National Cemetery. On the other hand, recent scholarship in 2010 by Michael Halleran shows that while Armistead and Bingham were both Masons, Bingham's encounter with Armistead occurred while the mortally wounded Armistead was being carried from the field by several men and happened purely by chance not because of any appeal of Masonic significance. Bingham never claimed otherwise. Bingham did take Armistead's personal effects and forwarded them to Major General Winfield S. Hancock as Armistead had requested because Hancock was a pre-war friend. Bingham also was wounded on July 3, 1863 at the Battle of Gettysburg. In 1864, Bingham became aide-de-camp to Major General Gouverneur K. Warren. During the Battle of the Wilderness during the VirginiaOverland Campaign, on May 6, 1864, as captain of Company G, 140th Pennsylvania Infantry, he "rallied and led into action a portion of the troops who had given way under fierce assaults of the enemy." He was awarded a Medal of Honor on August 26, 1893, for these actions. Bingham was wounded again at the Battle of Spotsylvania, May 12, 1864. On September 25, 1864, Bingham was discharged from his company for promotion and appointed Major and Judge Advocate of the First Division. Bingham was captured at Dabney's Mill, Virginia on October 27, 1864 during the Battle of Fair Oaks & Darbytown Road but escaped the same day. Bingham was wounded a third time during his service at Farmville, Virginia in 1865. Bingham was mustered out of the service on July 2, 1866 and returned home to Philadelphia. On December 3, 1867, President Andrew Johnson nominated Bingham for appointment to the brevet grade of brigadier general of volunteers, to rank from April 9, 1865, and the U.S. Senate confirmed the appointment on February 14, 1868.
Rank and organization: Captain, Company G, 140th Pennsylvania Infantry. Place and date: At Wilderness, Va., May 6, 1864. Entered service at: Cannonsburg, Pa. Born: December 4, 1841, Philadelphia, Pa. Date of issue: August 31, 1893. Citation:
Rallied and led into action a portion of the troops who had given way under the fierce assaults of the enemy.