2nd Pennsylvania Heavy Artillery The 2nd Pennsylvania Heavy Artillery was a heavy artillery regiment that fought in the Union Army during the American Civil War . It was the largest regiment to serve in the Union Army , with over 5 , 000 officers and enlisted men in its ranks at one time or another - in fact , while it was recruiting , there were so many applicants that another regiment was created to take the excess men : the 2nd Pennsylvania " Provisional " Artillery . History . Recruitment for the regiment started in October 1861 from the city of Philadelphia and the counties of Franklin , Allegheny , and Monroe . Charles Angeroth was the regiment ' s first colonel , John H . Oberteuffer , Sr . was the lieutenant colonel , and William Candidus was the major . Ten companies were mustered in on January 8 , 1862 , and ordered to Washington , D . C . They spent the next two years constructing and garrisoning various fortifications around the city , including Fort Stevens . Angeroth resigned in June 1862 and was replaced by Augustus A . Gibson of the 2nd U . S . Artillery as colonel . Candidus also resigned in August and was replaced by James L . Anderson . In November , two more companies were added to the regiment , raising the total strength to 1 , 800 men in twelve companies . In February 1863 , the regiment was formally assigned to the XXII Corps , Department of Washington , first as part of the 1st Brigade , Haskins ' Division , and later of the 1st Brigade , DeRussy ' s Division . So many recruits joined the regiment that by the spring of 1864 , it numbered over 3 , 300 officers and enlisted men . Since the army needed troops at the front lines , on April 20 , the War Department ordered the " surplus " officers and men to form a second regiment , the 2nd Pennsylvania Provisional Heavy Artillery . This provisional regiment was sent to the Army of the Potomac as part of the IX Corps . The original regiment was assigned to that army as well on May 27 as part of the XVIII Corps . It arrived at Cold Harbor on June 4 but did not participate in the battle . Too large to operate as a single unit , it was divided into three four - company battalions . The 2nd saw its first battle on July 15 , when the XVIII Corps made some of the first assaults in the Siege of Petersburg . Gibson was replaced on July 21 by Anderson . The regiment fought in several battles and skirmishes for the next several months , often losing heavily . For example , it lost 465 men at the Battle of Chaffin ' s Farm alone . Its losses were replaced somewhat by the consolidation of the 2nd Provisional Regiment back into the original regiment . During an attack on Fort Harrison , Anderson was killed and Sadler was captured . With no field officers left , new ones were appointed from the company commanders . Captain William M . McClure of Company F was appointed colonel , Captain S . D . Strawbridge lieutenant colonel , and Captain Benjamin F . Winger , major . In January 1865 , the regiment reenlisted and , with additional recruits , numbered 2 , 000 officers and men . McClure was honorably discharged on March 7 . Strawbridge succeeded him to command of the regiment , Winger was promoted to lieutenant colonel , and Captains David Schooley and William S . Bailey to major . After the breakthrough at Petersburg on April 2 , it was assigned to provost duty in the city . After the Confederate surrender at Appomattox Court House , the companies were scattered around southeastern Virginia to maintain order . The 2nd was finally mustered out on January 29 , 1866 at City Point , Virginia , and was discharged at Philadelphia on February 16 .