The John R. Cason Papers consist of only one journal with copied letters and lists as well as signatures of Confederate officers at Point Lookout, Maryland, during the American Civil War. The journal is divided into four sections.

The first section, starting on page [ii], is a list of the "Names of officers confined at Point Lookout Md. Feb 22nd/64." Fifty-nine officers signed their names, ranks, units, and sometimes places of capture in this section, including John O. Murray who would go on to write a book about the Immortal 600.

The second section, starting on page 21, contains five letters addressed to Cason written on March 2 and 3, 1864.

The third section, starting on page 31 contains "A list of Confederate States officers under fire on Morris Isle Sept 7th to Oct. 21st 1864." This list contains the name, rank, regiment, place of capture, and place of residence for every officer in the Immortal 600, ordered by state and name. This section also includes lists of the men who were hospitalized after their experience on Morris Isle, who escaped before reaching Morris Isle, and who were exchanged or removed from Morris Isle. At the end of the third section is a table tabulating the fates of the Immortal 600 by state.

The fourth section, starting on page 58 contains another seven letters addressed to Cason written February 28-March 1, 1865.