THE ERA OF INDUSTRIAL ASCENDANCY: 1861-1945
After 1861 Pennsylvania's influence on national politics diminished gradually, but its industrial complex grew rapidly.
The Civil War
During the Civil War, Pennsylvania played an important role in preserving the Union. Southern forces invaded Pennsylvania three times by way of the Cumberland Valley, a natural highway from Virginia to the North. Pennsylvania shielded the other northeastern states.

Pennsylvania's industrial enterprise and natural resources were essential factors in the economic strength of the northern cause. Its railroad system, iron and steel industry, and agricultural wealth were vital to the war effort. The shipbuilders of Pennsylvania, led by the famous Cramp Yards, contributed to the strength of the navy and merchant marine. Thomas Scott, as Assistant Secretary of War, directed telegraph and railway services. Engineer Herman Haupt directed railroad movement of troops and was personally commended by President Lincoln. Jay Cooke helped finance the Union cause, and Thaddeus Stevens was an important congressional leader. Simon Cameron was the Secretary of War until January 1862.

No man made a greater impression as a state governor during the Civil War than Pennsylvania's Andrew Curtin. At his first inaugural he denied the right of the South to secede and throughout the war was active in support of the national draft. In September 1862, he was the host at Altoona to a conference of northern governors which pledged support to Lincoln's policies.

Nearly 350,000 Pennsylvanians served in the Union forces, including 8,600 African American volunteers. At the beginning, Lincoln's call for 14 regiments of volunteers was answered by 25 regiments. In May 1861, the Assembly, at Curtin's suggestion, created the Pennsylvania Reserve Corps of 15 regiments enlisted for three years' service. They were mustered into the Army of the Potomac after the first Battle of Bull Run, and thousands of other Pennsylvanians followed them. Camp Curtin at Harrisburg was one of the major troop concentration centers of the war. Admiral David D. Porter opened the Mississippi and Rear Admiral John A. Dahlgren made innovations in ordnance which greatly improved naval fire power. Army leaders from Pennsylvania were numerous and able, including such outstanding officers as George B. McClellan, George G. Meade, John F. Reynolds, Winfield S. Hancock, John W. Geary, and John F. Hartranft.

After the Battle of Antietam, General J.E.B. Stewart's cavalry rode around General George McClellan's army and reached Chambersburg on October 10, 1862. There they seized supplies and horses, burned a large storehouse, and then withdrew as rapidly as they had come.

In June 1863, General Robert E. Lee turned his 75,000 men northward on a major invasion of Pennsylvania. The state called up reserves and volunteers for emergency duty. At Pittsburgh the citizens fortified the surrounding hills, and at Harrisburg fortifications were thrown up on both sides of the Susquehanna. Confederate forces captured Carlisle and advanced to within three miles of Harrisburg; the bridge at Wrightsville had to be burned to prevent their crossing. These outlying forces were recalled when the Union army under General George G. Meade met Lee's army at Gettysburg. In a bitterly fought engagement on the first three days of July, the Union army threw back the Confederate forces, a major turning point in the struggle to save the Union. Not only was the battle fought on Pennsylvania soil, but nearly a third of General Meade's army were Pennsylvania troops. Governor Curtin led the movement to establish the battlefield as a memorial park.

In 1864, in retaliation for Union raids on Virginia, a Confederate force under General John McCausland advanced to Chambersburg and threatened to burn the town unless a large ransom was paid. The citizens refused, and Chambersburg was burned on July 20, leaving two-thirds of its people homeless and