In January of 1941 Frank Walker was asked to deliver unofficial messages from some members of the Japanese government to President Roosevelt. The request came from Father James M. Drought and Bishop James Edward Walsh, two members of the Maryknoll foreign mission society whose work in Japan had brought them into contact with Tadao Wikawa (also called Paul Wikawa), a prominent Japanese banker with close ties to his government. Walker agreed to serve as an intermediary between the United States government, primarily Secretary of State Cordell Hull, and the Japanese government. The subjects of the negotiations were the strained relations between the two countries and possible agreements that might ease the tensions. Roosevelt asked Walker to make unofficial contacts with the Japanese embassy and to reduce to writing whatever proposals the Japanese made. The records from these negotiations include accounts of meetings, correspondence among the participants, memoranda to Roosevelt and Cordell Hull, chronologies of events, position papers, texts of cables, and newspaper clippings on Japanese- American relations. Most of the contacts were by telephone or personal interview and few written communications were exchanged. Also included in this series are records generated after World War II as historians and Congress investigated the events leading up to the attack on Pearl Harbor. Included in this category are correspondence, excerpts from books on the topic, accounts of the events by various participants, and testimony and reports from the 1946 congressional investigation into the Pearl Harbor attack. Walker's own account of the negotiations and related events can be found in the Memoirs Series (boxes 122-125).

• CWLK 99/01 File : Telephone and Appointment Log 1941
• CWLK 99/02 File : Memoranda, January- March 1941
• CWLK 99/03 File : Correspondence and Proposal Drafts, May- July 1941
• CWLK 99/04 File : Correspondence, telegrams, notes, proposals 1941-1954
• CWLK 99/05 File : Document List, Correspondence, Memoranda, March-July 1941
• CWLK 99/06 File : Correspondence, clippings, March- July 1941
• CWLK 99/07 File : Correspondence and proposals, May- November 1941
• CWLK 99/08 File : Notes, Memorandum, Correspondence, June-July 1941
• CWLK 99/09 File : Correspondence, Memoranda, September 1941
• CWLK 99/10 File : Bishop Walsh's statement, October 1941
• CWLK 99/11 File : Bishop Walsh Memorandum, 12/15 1941
• CWLK 99/12 File : Memorandum and Correspondence 1941-1949
• CWLK 99/13 File : Brief Case of Tadao Wikawa 1941
• CWLK 99/14 File : Contents of Inner Sleeve of Tadao Wikawa Brief Case 1940-1941
• CWLK 99/15 File : Contents of Tadao Wikawa Brief Case 1941-1946
• CWLK 99/16 File : Envelope containing Japanese money from Brief Case 1941
• CWLK 99/17-18 File : Correspondence, Memoranda, Reports 1940-1955
• CWLK 99/19 File : PEACE AND WAR: US FOREIGN POLICY, 1931-1941 1942
• CWLK 99/20 File : Miscellaneous Press Clippings 1942-1946
• CWLK 99/21 File : Correspondence- Fr. James Drought, MM 1941-1942
• CWLK 99/22 File : Memoranda and Clippings 1952-1953
• CWLK 99/23 File : Photocopies of Congressional Report on Pearl Harbor 1941-1949
• CWLK 99/24 File : The X Memorandum 1945
• CWLK 99/25 File : Hull Statement to Joint Committee on Pearl Harbor 1945-1946
• CWLK 99/26 File : Bishop Walsh Affidavit to International Tribunal 1947
• CWLK 99/27 File : Memoranda 1941-1949
• CWLK 99/28 File : Memoranda, Clippings 1952
• CWLK 99/29 File : Notes, Memoranda 1953
• CWLK 99/30 File : Memoranda, clippings 1953
• CWLK 99/31 File : Excerpts from THE UNDECLARED WAR 1953
  • CWLK 99/31 Author : William L. Langer and S. Everett Gleason 1953

In 1946 Frank Walker accompanied Secretary of State James Byrnes, Eleanor Roosevelt, and Edward R. Stettinius, Jr. to London as a member of the United States delegation to the first session of the United Nations (U.N.) following the adoption of the group's charter at the San Francisco Conference in 1945. Walker's records from these meetings include correspondence, his diary for December 1945 to February 1946, reports of the United States delegation, memoranda reporting meetings with other delegations, U.N. General Assembly resolutions and amendments, lists of U.N. committees and minutes from their meetings, a digest of world press comments on the U.N., and press releases. Correspondents include other members of the United States delegation, organizations and individuals interested in world cooperation, delegates from other countries, and U.N. officials. Walker's work with the United Nations Organization and the U.N. delegation was his last act of public service before returning to his family business and personal interests. Newspaper clippings concerning United Nations activities of this period can be found in the Scrapbook Series.

• CWLK 99-100 Subseries : UNO Correspondence, Memoranda, Walker Diary 1945-1946
  • CWLK 99/32 File : A 1945-1946
  • CWLK 99/33 File : Atomic Bomb 1945-1946