Twenty-five hundred men and boys from Mercer County served in the Civil War, then called the "War of the Rebellion," in regiments including the 39th, 10th Reserves, 57th, 76th Keystone Zouaves, 77th, 100th Roundheads, 111th, 139th, 140th, 142nd, 145th, 169th, 211th, and 212th, including companies such as Co. B Middlesex Rangers, G Mercer Rifles, C, E Verner Greys, E Bell's Guards, B and G Worth Guards, A Mercer Guards, B Stewart's Infantry, and I and M of the 6th Heavy Artillery; smaller numbers from Mercer County also served in the 83rd PVI, 134th PVI, and 4th Pa. Cav. (64th Rgt.).