The papers of John Wills Greenslade (1880-1950) span the years 1847-1961, with the bulk of the items concentrated in the period 1895-1952. The collection contains correspondence, writings, memoranda, printed matter, photographs, scrapbooks, and other material documenting Greenslade's career as a naval officer from the Spanish-American War through World War II, notably during the North Sea mine barrage, 1917-1918; as chief of staff, Battleships Division, 1929-1930; commander, Submarine Force, 1932-1934; as senior member of the President's Board to Select Base Sites in British Possessions, 1940-1941; and as commander of the Western fleet from 1942 to 1944. The papers are arranged into the following series: Diaries , Correspondence , Speeches and Writings , Subject File , Miscellany , and Oversize .

The Diaries contain originals and copies of letters from Greenslade to his mother, Nell Wills Greenslade, and sister, Sophia J. Greenslade, from the United States Naval Academy and subsequent voyages, including duty in the Philippines aboard the gunboat Concord, 1895-1900; the log of the cruiser Chicago, 1899-1901, the gunboat Princeton, and others, 1901-1904; and diaries of the cruise of the collier Vulcan in 1914; personal and private diary from the mine layer Housatonic, 1918; and notes from his trip to Baku aboard the destroyer Cole, 1919-1920. Further material on the Housatonic is in the Subject File under North Sea mine barrage and in a photograph album in the Miscellany .

Correspondence includes administrative and general correspondence as well as letters of congratulation and sympathy. Correspondents include W. A. Bostwick, A. S. Halstead, Frederick J. ("Fritz") Horne, Royal E. Ingersoll, Ernest Joseph King, Frank Knox, William D. Leahy, Richard H. Leigh, Chester W. Nimitz, John F. Slavich, Joseph K. Taussig, J. Frank Taylor, and Earl Warren. Also included are letters from his son, John F. Greenslade, also a naval officer, written primarily between 1923 and 1936.

The Speeches and Writings series contains speeches and addresses on naval questions, command issues, and world affairs, with related correspondence, delivered between 1927 and 1948, articles on naval matters written between 1931 and 1944 for various publications, and theses and papers written at the Naval War College between 1925 and 1928.

The Subject File includes correspondence, dispatches, and memoranda which document Greenslade's tenure as chief officer of a commission to locate naval and air base sites in British possessions in 1940 and 1941. Files for each location include memoranda, charts, and aerial photographs. Correspondents in these files include William H. Beck, Stanley Truman Brooks, Edward, Duke of Windsor, Philip Henry Kerr, marquis of Lothian, Gordon J. Lethem, and Herbert Pott.

The Subject File also includes material related to the North Sea mine barrage and Greenslade's command of the mine layer Housatonic between 1918 and 1919. His personal and private diary from the Housatonic is found in the Diaries series. Other files include memoranda, correspondence, cables, and printed matter relative to naval operations, submarine force command issues, and the cruise of the collier Vulcan, which dealt with a dispute about the German ship Waltraute and payment for its cargo of coal in 1914-1915. Topics also include the Pacific Coast Joint Committee for Shipbuilding and Ship Repair, the Naval Shore Establishment Board, the United States Naval Academy, and the Naval War College, which Greenslade headed between 1926 and 1928.

The Subject File contains correspondence with John Reber concerning the "Reber Plan" for development of the San Francisco Bay area, Greenslade's résumé of service, correspondence and memoranda concerning Greenslade's duty status and disability retirement, and honors and decorations of both Greenslade and his son, John F. Greenslade. Other material includes a map and newspaper from Veracruz, Mexico, 1856-1957, typescripts of naval history documents, and correspondence relating to the donation of the Panton-Innerarity Papers, Florida history documents originally belonging to Greenslade's mother, to the Florida Historical Society.

The Miscellany includes photograph albums documenting official naval activities, specifically cruises of the Housatonic, cruiser Galveston, mine layer Shawmut, battleship Maryland, and others, the selection of base sites in British possessions, Greenslade's visit to the Kaiser Shipyards in Richmond, California, the Naval Proving Ground in Indian Head, Maryland, and the dedication of two ships by his third wife, Alma Greenslade. Three photograph albums, dated 1896-1933, including personal and family photographs, and a scrapbook of Greenslade's travel on the airship Hindenburg in 1936 have been transferred to the Prints and Photographs Division.

The Miscellany also includes assorted printed matter in the form of scrapbooks for the years 1895-1952, clippings about Greenslade, invitations, programs, proclamations, and a reading file of articles, monographs, and periodicals on military and foreign affairs.