On August 1, 1861, the 39th was sent to Tennallytown, Maryland, and after a short service at Great Falls was assigned to the 3rd brigade. This brigade made its winter quarters at Langley, Virginia; they fought at Dranesville in December 1861, then they were ordered to the Peninsula in the spring, 1862. They took part in the battles of Mechanicsville, Gaines Mill, Glendale, the second Bull Run, Battles of South Mountain, Antietam, Fredericksburg, and won many laurels. After Fredericksburg, the Reserves were ordered to Washington to recuperate. In June of 1863, they fought side by side with their old comrades of the 3rd and 38th brigades at Gettysburg. After the battle, they pursued Lee south. The regiment remained with the Army of he Potomac through the winter, and took part in the Mine Run campaign. When spring came during the month of May 1864, they were engaged in the Battle of the Wilderness, Spotsylvania, Totopotomony and Bethesda Church. Soon after the veterans and recruits were transferred to the 190th and 191st Pennsylvania Infantry, they were returned to Pittsburgh, where they were mustered out June 11, 1864.
