After studying at Phillips Academy, Danville, in
Vermont, and at
Russell Military Academy in
New Haven, Connecticut, he joined the
Union Army as captain of the
Richmond City Greys—
volunteers for service in the
American Civil War. Dudley's company was incorporated into the
19th Indiana Volunteer Regiment of the famed
Iron Brigade of the
Army of the Potomac. During the Second Battle of Bull Run, Dudley captured a Lt Cosson who was wearing spurs that had been a gift from
Robert Toombs; Dudley wore the spurs but promised that he was captured he would return them to Cosson. At age 19, at the
Battle of Antietam, he took command of the regiment after the death of Lieutenant Colonel
Alois O. Bachman. Following the battle, Dudley was quickly promoted to Major (September 18, 1862), and then Lieutenant Colonel (October 6, 1862). After losing 79 percent of his men at the
Battle of Gettysburg, and having his right leg
amputated on the field, he served as an army inspector and
judge advocate and captain in the
Veteran Reserve Corps. For gallantry in battle, he was awarded an honorary
brevet to Brigadier General of Volunteers on March 13, 1865. Following the end of the war he became a civilian lawyer in 1870, then the
U.S. marshal for
Indiana in 1879, commissioner of pensions under appointment of Presidents
James Garfield and
Chester A. Arthur in 1881. In 1888 he was appointed Treasurer of the
Republican National Committee. He returned to practicing law in 1887. ==1888 election controversy==