War Diary

On October 19, 1942 the Commander in Chief of the Navy issued new guidance to the fleet regarding the ship’s logbook. His order, COMINCH 3899, directed that the logbook be divided into three sections: Part I Columns (the weather page); Part II Administrative Remarks (routine business like personnel changes), and; Part III Operational Remarks (War Diary) CONFIDENTIAL. Part III was to be kept separate from the other two sections. A typical example is shown in Fig. 1. It is notable that this document series was only formally declassified by the National Declassification Center a few years ago.

The purpose of this change was to decrease the likelihood that useful intelligence could be gleaned if the ship’s logbook fell into the wrong hands. In the first days of the war there were six U.S. Navy ships that were scuttled in shallow water and later salvaged by the Japanese Navy, and one captured outright, the USS Luzon (PR-3). During 1942 several S-class submarines were also accidentally grounded and abandoned in hostile territory. But perhaps the stunning success of the British Royal Navy capturing German naval codebooks and all-important Enigma machines in 1941 was the main inspiration. More about this in The Guardian.

Figure 1. An example of a War Diary from the destroyer USS Macdonough from 1 November 1943. On this day the Macdonough departed Pearl Harbor to join Task Force 52 en route to the Gilbert Islands and the invasions of Tarawa and Makin Island.

The key point for our purposes is after late 1942 the navigation data does not appear on the Part I weather page except as a single noon notation expressed only in whole degrees. The detailed navigation data was moved to the War Diary. The 3899 directive was in force until the spring of 1944, when the logbook format returned to something close to the historical pattern, insofar as the navigation data was moved back to the weather page.

Due to the time lag in getting new format log sheets out to the fleet in 1942, and again in the spring of 1944, there is considerable variance in when a particular ship’s logbook reflects these changes. Moreover, when COMINCH 3899 was issued, there were no pre-printed sheets for the new scheme available at all, so for several months the War Diary was typed out on a blank sheet that roughly followed the new instructions.

All this means that the workflow we’ll use to capture the navigation data during this period will need to be quite flexible. However, a benefit for those interested in the ship’s stories is that the War Diaries will soon be part of a new Navigation workflow. As you will see, these first-hand accounts can be extraordinarily compelling, even when written in the normally dispassionate language of the ship’s logbook.

Finally, the separation of the navigation data from the weather pages of the logbook may have affected the amount of U.S. Navy weather data originally key-punched by the Weather Bureau in the early 1950s, and later migrated into the present International Comprehensive Ocean-Atmosphere Data Set (ICOADS). Since only weather observations associated with a ship’s position were punched, loss of collation with the navigation data may well be a factor. Departures in the number of observations per day captured in ICOADS during and after the period COMINCH 3899 was in force (Figure 2) is suggestive of such a loss. This further supports the need for the data (and metadata) recovery we are working on together.

Figure 2. Time-series of the number of U.S. Navy daily weather observations key-punched by the Weather Bureau and migrated into ICOADS Deck 195. Marked changes in the number of observations captured per day occur at the beginning and end of the period COMINCH 3899 was in force, and most dramatically at the conclusion of the war in Europe (VE), when the Navy rapidly drew down the number of ships in the Atlantic Ocean.