Most of the correspondence included in this collection is from Stillwell to his father, Jeremiah O. Stillwell. These letters, dating from January, 1863 to the end of December, 1863, relate Stillwell's military experience to his father. Later correspondence, dating from 1898 to 1920, is from various political figures to Stillwell asking for favors, endorsements, or his opinions.

The diary entries are varied and detailed. Mitchell records an eclipse of the moon, observes the course of the war and the politics involved in it. He also observes military life, the prevalence and fatal consequences of diseases such as measles and mumps, the physical and demographic features of the country through which he traveled. There are lists of all the members of his company, their nativity and home towns.