The Clark Papers contains eight letters, seven of which were written by John A. Clark to William Wesley Whedon (1827-1907), of Chelsea, Michigan, and his wife, Helen Turner. One letter, written by Clarence Whedon, William's brother, includes a good description of the Battle of Fredericksburg. Clarence served in the 20th Michigan Infantry
Clark's letters are highly literate accounts of the cavalry service during the Civil War, filled with descriptions of the strenuous, active and mobile life of the horse soldier. His letters describing the days before and after the Battle of Gettysburg, and his 14 page letter describing the Appomattox Campaign and the close of the war in the east are memorable. His letter of August 10th, 1863, includes a description of counter-guerrilla activity in the Shenandoah Valley that highlights the brutality and uncertainty of guerrilla warfare and the sometimes extralegal means to which Federal troops had to resort to suppress the guerrillas.