Doré was born on the Isle of Wight in England on 24 June 1845. He enlisted into the 126th New York Infantry from West Bloomfield, New York on 22 August 1862. He was made prisoner following the Battle of Harpers Ferry, but paroled a day later. After his act of gallantry earned him the Medal of Honor on 3 July 1863 at the Battle of Gettysburg, he was promoted to corporal in December 1863 and sergeant in June 1864. He mustered out with his regiment on 3 June 1865.