In April 1861, in response to the firing on Fort Sumter, President Abraham Lincoln called for seventy-five-thousand volunteers to fill the ranks of the U.S. army. The response was immediate and overwhelming. Men residing in the northern states enlisted in such numbers that thousands had to be turned away, many then joining units from other states. During the first two years of the war, Illinois mustered over eightythousand men into Federal service. Of these men, seventeenthousand or 21 percent came from the fourteen northern most counties of the state, excluding Cook County. During the first two years of the war, over one-quarter of all military-age males from northern Illinois enlisted.