McCafferty kept a diary in which he made near-daily entries from April 8, 1942, the day before the surrender of Bataan, until the Japanese surrender in 1945 and the liberation of prisoners of war. The collection includes 15 notebooks and notepads which document McCafferty’s life in Japanese prison camps. McCafferty wrote in a sloppy and cramped hand in order to make the diary indecipherable to the Japanese authorities, and also due to the scarcity of writing supplies (he often fits two lines of script into one ruled line on the page). Accompanying the handwritten diaries is a typescript which McCafferty later made, consisting of 17 numbered and dated sections and one undated section, being a reflection on his Japanese captors and a list of their names and/or nicknames and personality traits. Most of the sections include an index of events. Also included in the collection is a photograph of McCafferty taken when he was a captain.

In the diary McCafferty describes his experience on the Bataan Death March, as a passenger aboard various transport ships bound for prisoner of war camps, and daily life in the camps. McCafferty records the many abuses prisoners were subjected to. Prisoners who failed to bow or show proper respect to their captors received beatings, or “boppings” in McCafferty’s words. McCafferty describes instances of Japanese sentries hiding in bushes to catch prisoners unawares, then beating them for failing to bow. Occasionally the prisoners were assigned essays on topics chosen by their captors, such as “who started the war?” and “the treatment of Japanese internees in the U.S.” McCafferty writes that shortened rations and punishment would follow if the essays displeased the Japanese authorities. Food, or lack thereof, is a constant theme in the diary. Sometimes McCafferty’s entry is little more than a description of the food ration that day. He records the men’s complaints over the size and quality of rations and fairness of food distribution, as well as describing the men’s efforts to supplement their diet, for instance, by foraging for snails. McCafferty also records the cramped and unsanitary conditions aboard Japanese transport ships, in which hundreds of men were squeezed into rat-infested cargo holds and forbidden from opening the portholes to get fresh air.