Letter of Henry Thurlow Bartlett (1839-1898), formerly a bugler in Companies H and F, 1st Massachusetts Cavalry during the American Civil War and later vice-president of the Cavalry Corps in the Society of the Army of the Potomac (S.A.P.), written to Samuel E. Chamberlain, president of Cavalry Corps, S.A.P., in 1888, urging the nomination of a cavalryman as the next S.A.P. president and describing the importance of cavalry at the Battle of Gettyburg.