John Aubin was born around 1843 in Canada to Francois Aubin and Adelaide Poudret dit Lavigne. The family immigrated to New York around 1850, and his father worked as a laborer. Aubin enlisted in the Union army on October 16, 1861, and mustered in as a private in Company A of the 97th New York Infantry later that day. The regiment took part in the Battles of Antietam, Fredericksburg, Chancellorsville, and Gettysburg. Confederate forces captured him at Gettysburg on July 1, 1863, and sent him to the prison camp on Belle Isle, Virginia. He died on May 1, 1865, either in the Andersonville prison camp or a parole camp in Annapolis, Maryland.