President Abraham Lincoln's call for 75,000 volunteers in April 1861 made it necessary for Indiana governor Oliver P. Morton to find a suitable location for receiving the state's volunteers to the Union cause. By the end of April 1861 the thirty-six-acre Camp Morton had shelters for six thousand men. In February 1862 the federal government took over the camp and turned it into a place to hold Confederate prisoners. The camp remained a prison camp until the end of the war.