This accession includes 113 letters, about 500 total pages, mostly from 1864 (1861-1866). These are letters that Endicott wrote during the Civil War to his family and friends in Canton, Massachusetts. His mother, A. Matilda Endicott, was the most frequent recipient of William's letters. He also wrote to his sisters, Mary Alice and Marion, and to his friend, Mary F. Messinger, who received letters throughout the period of correspondence. Several other letters are included involving other friends or members of the family. Many of them refer to William, or contain related material to him. All of the letters are arranged chronologically. The letters are full of observations, poetry, drawings, sketches social commentary, and accounts of camp life.