This is the second volume of a projected set of five. The first volume, Anglo-American Naval Relations, 1917–1919, was published in 1991; since then, other studies have supervened. It is now intended to complete the series, down to 1945. The scheme is for Mr Robin Brodhurst, author of a biography of Admiral of the Fleet Sir Dudley Pound, to edit the two volumes corresponding to Pound's time as First Sea Lord – June 1939 to October 1943. It is intended that I should edit the volume for 1943 to 1945.

The years between 1919 and 1939 were dominated by a series of naval arms limitation and disarmament conferences and the first four Parts of this volume acknowledge this. Part V, ‘The Sailors Meet’, deals with the encounters of serving officers and men of the two navies and their observations on each other's navy. Finally, Part VI, ‘Edging towards an Alliance’, details the hesitant and limited steps towards co-operation between 1937 and 1939 when a second world war looked increasingly likely.

The materials used for the Royal Navy have been drawn from the Admiralty papers at The National Archives, Kew, London; the National Maritime Museum, Greenwich, London; and the Churchill Archives Centre, Churchill College, Cambridge. For the United States Navy, I have drawn on The National Archives, Washington, DC; the Operational Archives, Naval Historical Center, Washington Navy Yard; The Manuscripts Division of The Library of Congress, Washington; and the Franklin D. Roosevelt Presidential Library, Hyde Park, New York. I have avoided using diplomatic or political documents where possible; many of the documents on foreign policy have been published in the series Documents on British Foreign Policy (London: HMSO, various) and Foreign Relations of the United States (Washington, DC: Government Printing Office, various).

Punctuation marks have been inserted on occasion to clarify passages or to mark omissions. At times, numbered paragraphs in official communications have been omitted, resulting in breaks in their sequence. Missing words are indicated thus: [——]. If there is some doubt about a word it is expressed thus: [? word]. Place names are contemporaneous. Places and dates of origin, where known or where appropriate, are placed at the head of documents. All Admiralty communications originated from London.