When news of the bombardment and subsequent surrender of Fort Sumter in Charleston, South Carolina reached Washington, D.C. on April 14, 1861, President Abraham Lincoln called for 75,000 volunteers to join the Army to quell the rebellion of the Southern states. Across the North, eager recruits responded to calls from local governmental officials to join newly raised state regiments. Governor Andrew Curtin of Pennsylvania issued a proclamation asking for 13,000 able-bodied men to volunteer to help preserve the Union. Within three days, thousands of men had converged at Harrisburg to enlist, but they had no formal place to organize or drill. Dauphin County officials offered Governor Curtin the use of the County Agricultural Society on the northern outskirts of Harrisburg for these volunteers. Maj. Joseph F. Knipe officially opened the camp on April 18, 1861, and named it Camp Curtin in honor of the governor (the planned name had been Camp Union). From December 1861 to March 1862, the camp was commanded by Truman Seymour.
Over 300,000 soldiers passed through Camp Curtin, making it the largest Federal camp during the Civil War. Harrisburg's location on major railroad lines running east and west, and north and south made it the ideal location for moving men and supplies to the armies in the field. In addition to Pennsylvania regiments, troops from Maryland, Michigan, Minnesota, New Jersey, New York, Ohio, Wisconsin, and the Regular Army used Camp Curtin. The camp and surrounding area also saw service as a supply depot, hospital and prisoner-of-war camp. At the end of the war, Camp Curtin was used as a mustering-out point for thousands of troops on their way home. It was officially closed on November 11, 1865.