The 155th Pennsylvania Volunteer Infantry Regiment was a Federal infantry regiment that served in the American Civil War in the Army of the Potomac in the Eastern Theater. Recruits from the Pittsburgh area organized at Camp Copeland from September 2–19, 1862, into the 155th Regiment, Pennsylvania Volunteer Infantry. Edward J. Allen served as the first colonel. After initial training and drilling, the regiment moved via train to Washington, D.C. where it joined the 2nd Brigade, 3rd Division of the Union Fifth Corps. It moved to Sharpsburg, Maryland, after the Battle of Antietam and then first saw combat in December 1862 at the Battle of Fredericksburg, where the color guard suffered very high casualties in an ill-fated assault.