The Henthorn papers consist of seven letters written by Henthorn to his father, Nelson, two to his younger brother, George, three to his sister, Sarah, and one letter from Nelson to George Henthorn. Charles Henthorn is an unusually powerful writer and provides thoughtful, evocative descriptions of the events unfolding around him. His observations on the varied roles of African Americans in the army are particularly noteworthy. They are depicted in several ways: as informers on Confederate sympathizers hiding from the Union Army, as victims of racism and southern hatred, and as highly motivated and effective soldiers at the Battle of Milliken's Bend. Henthorn appears to have a much more positive attitude toward blacks than many of his fellow soldiers, and he appears equally to be aware of this fact.
Equally interesting are Henthorn's descriptions of the land itself, including fine descriptions of towns in Indiana and Ohio, and of evacuated plantations in Louisiana. He makes several references to hostile southern attitudes toward the Union troops, and describes an instance of pillaging by members of his regiment. There are two second-hand accounts of battles, the Battles of Richmond and Milliken's Bend, but by and large, there is very little martial content in Henthorn's letters. He is instead at his best in his reflections on the effect of the conflict on the soldiers and civilians. The final two letters in the collection provide (respectively) an insight into the depth of Henthorn's religiously held pro-Union, anti-slavery views, and an account of a copperhead rally in Lacon during the 1864 presidential election which featured a coffin containing a likeness of Lincoln with buzzards flying overhead.