In May 1861, he enlisted in the 3rd New Jersey Volunteer Infantry. Commissioned as a first lieutenant, he would ultimately be promoted to captain and served as an aide to Brig. Gen. George W. Taylor during the 1862 Peninsula Campaign, where he contracted typhoid and was confined to a hospital ship shortly after the Battle of Malvern Hill. He would not rejoin the brigade until shortly before their successful assault on Crampton's Gap, during the lead-up to Battle of Antietam. The VI Corps (ACW) was mostly held in reserve during the battle, though Edward later wrote that his men were convinced they could have finished Lee's army if properly employed.