For many people, Pennsylvania's contribution to the Civil War goes little beyond the battle of Gettysburg. Pennsylvania however, played a key role during the Civil War. Its industrial enterprise and natural resources were essential factors in the economic strength of the northern cause. The 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, including the Civil War's first submarine, Alligator, was built at the Neafie & Levy Shipyard in 1861-1862. Thomas Scott, as Assistant Secretary of War, directed telegraph and railway services. Engineer Herman Haupt directed railroad movement of troops. Jay Cooke helped finance the Union cause, and Thaddeus Stevens was an important congressional leader.
Administration of military affairs during the war was directed by two Pennsylvanians: first by Simon Cameron, who resigned his seat in the U. S. Senate to become President Lincoln's first Secretary of War; he was succeeded by Edwin M. Stanton of Pittsburgh.
Throughout the war, Pennsylvania politics were dominated by Governor Andrew G. Curtin, a strong supporter of President Lincoln. The extreme southern tier of the state however, included a fair number of Copperheads, particularly in Fulton, Adams, and York counties. As many as 2,000 Pennsylvanians defected to the Confederacy and during the advance of Lee's army in 1863, residents of the Gettysburg area gained a reputation throughout North and South as a stingy people who wanted to make money from the war rather than sacrifice for the Union.