William Gamble was born at Duross, County Tyrone, Ireland, on January 1, 1818. He studied civil engineering and practiced this profession in northern Ireland before emigrating to the United States about 1838. The year following he enlisted in the Regular Army and was successively private, corporal, sergeant, and sergeant major of the 1st Dragoons (later renamed the 1st Cavalry), until he received his honorable discharge in 1843. He then went to Chicago, where he worked as a civil engineer until the outbreak of the Civil War. In September, 1861, Gamble became lieutenant colonel of the 8th Illinois Cavalry and its colonel on December 5, 1862. The regiment's first war service was at Warrenton, Virginia, where it was stationed until the beginning of the Peninsular campaign. At Malvern Hill, Gamble was severely wounded in the chest and did not rejoin his command until the battle of Fredericksburg. By January 31, 1863, he was in command of a brigade, and on the first day of the battle of Gettysburg a vedette of his old regiment posted on the Cashtown Road fired the opening shot of that famous engagement. At the beginning of U. S. Grant's Overland campaign in May, 1864, Gamble was relieved from duty with the Army of the Potomac and assigned to the command of the cavalry division in the Department of Washington, where he served until the end of the war. Brevetted brigadier general of volunteers to rank from December 14, 1864, he was honorably mustered out of service on July 17, 1865. He was re-mustered shortly thereafter and on September 25, 1865, was appointed a full brigadier general of volunteers. Again mustered out in March, 1866, General Gamble was appointed major of the 8th Cavalry in July, 1866, when the postwar army reorganization was effected. That autumn his regiment was ordered to California. While accompanying it there via the Central American Transit route, he fell ill of cholera and died in Virgin Bay, Nicaragua, on December 20, 1866. He was buried there in Virgin Grove Cemetery where, according to the Memorial Division of the Quartermaster General's Department, his remains still repose.
Reference: Generals in Blue. Lives of the Union Commanders by Ezra J. Warner. Louisiana State University Press. Baton Rouge.