During the American Civil War, Pennsylvania was the second largest state in the Union, and Harrisburg was the state's capital.[1] Located at the intersection of important railroads, Harrisburg proved an important supply and logistics center for the dissemination and transportation of materiel for the Union Army. Tens of thousands of new recruits were mustered into service or drilled at a series of Harrisburg-area United States Army training camps, including the sprawling Camp Curtin. Confederate forces under Lieutenant General Richard S. Ewell threatened Harrisburg during the June 1863 Gettysburg Campaign, but were instead called by General Robert E. Lee to return to Gettysburg campaign. Pennsylvania Governor Andrew Curtin ordered local workers to erect a series of forts and earthworks to protect the city, which then had a population of 13,000 residents.[2]