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One interesting topic that people like to research is the period between the World Wars, and how the United States evolved from an equal ally of Western Europe at the end of World War I to the Arsenal of Democracy in World War II. The U.S. Navy is a great example of how world events contracted and inflated the service as it was struggling to meet the demands of restrictive naval limitation treaties, while also protecting the United States and its far flung territories across the Atlantic and Pacific as an emerging global maritime power. Emerging from the Great War with budget cuts and surplus vessels, the Navy entered a period of innovation characterized by the development of new technology balanced by a “make do” mentality. They experimented with primitive aircraft carriers and early naval aircraft and made improvements on submarines, the definitive weapons of the next war.


The Office of the Secretary of the Navy was also influential in the management and protection of United States territorial holdings like Puerto Rico, the Virgin Islands in the Atlantic, and Guam, Midway, Hawaiian Islands, and the Philippines in the Pacific. While maintaining the uncomfortable balance between budget cuts and the increasing threat of war in both oceans, the Office of the Secretary of the Navy shifted priorities from the build up of naval bases in these remote bases to planning the logistical framework of the next war.


A great resource for beginning research on the interwar U.S. Navy is with the General Correspondence of the Secretary of the Navy. The general correspondence includes letters, memoranda, and other reports from different parts of the Navy, including the assistant secretaries of the Navy, bureau heads, the Chief of Naval Operations, and the Judge Advocate General. The correspondence also includes letters to and from other parts of the government, including President Franklin D. Roosevelt and the U.S. Army.


The best starting point for accessing the correspondence is M1067: Name and Subject Index to the General Correspondence of the Office of the Secretary of the Navy, 1930-42. This series of index cards was originally microfilmed and made available in the microfilm room at the National Archives in Washington, DC. The microfilm has now been digitized and is available in the National Archives Catalog. This series consists of 187 rolls of microfilm listing names and subjects alphabetically. Each card relates to a name or subject, has a brief line about the letter, the date of the letter, and the Navy Filing Manual designation it is filed under.


Once you have the dates and Filing Manual designations from the microfilm series, you can use this information to search through the two general correspondence series: the General Files, 1926-40, or the General Correspondence, 1940-42. Both series are arranged according to the Navy Filing Manual.


Please note, the General Files series starts in 1926, but the index does not start until 1930. The Office of the Secretary of the Navy believed there would be no reason to index the correspondence following the publication of the Navy Filing Manual in 1925. By 1930, however, the Office had more correspondence than could be navigated with just the filing manual, and thus created an index. The division of the two series in 1940 corresponds to the beginning of World War II.


The two general correspondence series contains correspondence of the Office of the Secretary of the Navy at the unclassified and restricted levels. Even at these lower classification levels, there is a broad span of topics regarding the interwar period, ranging from new constructions to planning policies. There are also cards about companies and individuals that helped build up the fleet in the period before the war. The cards also include topics related to gender and race topics including developing policies on women and African Americans serving in the Navy or in the Naval Reserve. There are many interesting gems in these records such as the expansion of the U.S. Navy through the planned, appropriated, and constructed new ships before December 1941 at different naval shipyards. There are copies of the 1940 appropriation bill, better known as the “Two-Ocean Navy” bill or the Vinson-Walsh Act, which lists all the new ships of the expanding Navy that would later impact the outcome of the Second World War.


For those interested in the events in the Pacific Theater and the developments of advanced bases, there are index cards for islands including Midway, Wake, and the Hawaiian Islands, and what was being planned for the Asiatic Fleet based in the Philippines. There are also several cards regarding war plans and fleet exercises.


In addition to the General Correspondence of the Office of the Secretary of the Navy, there are also the Formerly Confidential and Secret Correspondence series of the Office of Secretary of the Navy. The 1927 to 1939 portion of the Formerly Confidential and Secret Correspondence share a single index. Although this index has not been digitized, it is similar in nature to M1067 in that it consists of name and subject index cards arranged alphabetically by topic. It is arranged in four parts: incoming correspondence, name and subject index, and outgoing correspondence are arranged alphabetically; and a second name and subject index is arranged according to  Navy Filing Manual designations. The name and subject portion of the index lists the topic and what correspondence is associated with it, what classification the correspondence is under, and what Navy Filing Manual designation it was given. Certainly, you can experiment with the Navy Filing Manual portion for the index too, and see what kinds of materials are under a particular Filing Manual designation.


The Formerly Confidential and Secret Correspondence are divided into two different series. Both series are arranged by the Navy Filing Manual. Since these correspondence series had been classified at a higher level, they should include more details on particular topics than the General Correspondence.


The Formerly Confidential and Secret Correspondence and indices for 1940 to 1947 dovetail to the earlier series.


The index to the later Formerly Security Classified Correspondence of the Secretary of the Navy and Chief of Naval Operations, 1940-47, is divided into several sub-sections by year blocks. Under each subsection, the index cards are divided into groups of incoming, outgoing, alphabetical by topic, and the Navy Filing Manual. The Formerly Security Classified Correspondence is divided into year blocks, then arranged by classification level, and then according to the Navy Filing Manual. You can explore the different formerly classified correspondence series by either using their respective index or utilizing the Navy Filing Manual designations.


In addition to the other correspondence series, the index and the general correspondence overlap with other microfilm collections of the Fleet Problems and the Records of the World Crisis, which have been discussion topics on the History Hub.


The correspondence series of the Office of the Secretary of the Navy from the interwar period to the early years of World War II illustrate the ebb and flow of national and naval policies in regards to international naval treaties, the shift from limiting naval construction to mass production into the expansion of the “Two Ocean Navy”, and from tentative budgeting for naval outposts to a mad rush to re-enforce them as the situation began to turn towards general war.


For information on the Index and the General Correspondence of the Office of the Secretary of the Navy, 1930-1942 and the Index and Formerly Confidential and Secret Correspondence of the Secretary of the Navy, 1927-39, please contact For questions about the Index and Formerly Security Classified Correspondence of the Secretary of the Navy, 1940-47, please contact