For permission to quote from several manuscript collections, I wish to thank Mrs. Chandler P. Anderson for the Chandler P. Anderson Diary; Miss Mabel Choate for Ambassador Choate’s letter; the Honorable Joseph C. Grew for his own papers; Mr. Arthur W. Page for the papers and diary of Ambassador Walter Hines Page; the Honorable William C. Phillips for his own papers; Houghton Library, Harvard University, custodian of the Grew, Page, and Phillips papers; and Yale University Library, custodian of the House and Polk papers.
   I would like to thank the New York Society Library for books, open stacks, and newspaper microfilms, and especially for that greatest of boons, an undisturbed place to write.
   To the anonymous reviewer of George F. Kennan’s book, Russia Leaves the War, who wrote in the Times Literary Supplement (London), January 4, 1957, this sentence, “We still do not know at any level that really matters, why Wilson took the fateful decision to bring the United States into the First World War,” I would like to say hello.
   March, 1958
   Code Text of the Telegram
   Edward Bell’s copy of the decode made at the American embassy (National Archives, Foreign Affairs Branch, State Department Decimal File, 862.20212/81½. English translation added by the author).
   This is the text, with Bernstorff’s slight alterations at the beginning, which Bernstorff forwarded to Eckhardt, and is the same as the text obtained by Admiral Hall in Mexico City which he gave to Ambassador Page.
   130 (number of telegram) —
   13042 (code identification number) —
   13401 Auswärtiges Amt Foreign Office
   8501 telegraphiert telegraphs
   115 Januar 16 January 16
   3528 colon(:) colon(:)
   416 number 1 no. 1
   17214 ganz geheim strictly secret
   6491 selbst yourself
   11310 zu to
   18147 entziffern decipher
   18222 stop(.) stop(.)
   21560 Wir We
   10247 beabsichtigen intend
   11518 am from the
   23677 ersten first
   13605 Februar February
   3494 un- un-
   14963 eingeschränkt restricted
   98092 U-boot U-boat
   5905 Krieg war
   11311 zu to
   10392 beginnen begin
   10371 stop(.) stop(.)
   0302 Es wird It will
   21290 versucht attempted
   5161 werden be
   39695 Vereinigten Staaten United States
   23571 trotzdem nevertheless
   17504 neutral neutral
   11269 zu to
   18276 erhalten keep
   18101 stop(.) stop(.)
   0217 Für den Fall In the event
   0228 dass dies that this
   17694 nicht not
   4473 gelingen succeed
   22284 sollte should
   22200 comma(,) comma(,)
   19452 schlagen offer
   21589 wir we
   67893 Mexico Mexico
   5569 auf on
   13918 folgender following
   8958 Grundlage terms
   12137 Bündnis alliance
   1333 vor (prefix of verb vorschlagen—to offer)
   4725 stop(.) stop(.)
   4458 Gemeinsam Together
   5905 Krieg war
   17166 führen make
   13851 stop(.) stop(.)
   4458 Gemeinsam Together
   17149 Friedenschluss peace
   14471 stop(.) stop(.)
   6706 Reichlich Generous
   13850 finanzielle financial
   12224 unterstützung support
   6929 und and
   14991 einverständnis understanding
   7382 unserer seits our part
   15857 dass that
   67893 Mexico Mexico
   14218 in in
   36477 Texas Texas
   5870 comma(,) comma(,)
   17553 New New
   67893 Mexico Mexico
   5870 comma(,) comma(,)
   5454 AR AR
   16102 IZ IZ
   15217 ON ON
   22801 A A
   17138 früher former
   21001 verloren lost
   17388 Gebiet territory
   7446 zurück back
   23638 erobern conquer
   18222 stop(.) stop(.)
   6719 Regelung Settlement
   14331 im in the
   15021 Einzelnen details
   23845 Euer Hochwohlgeboren Your Excellency
   3156 überlassen to be left
   23552 stop(.) stop(.)
   22096 Sie You
   21604 wollen will
   4797 vorstehendes of the foregoing
   9497 dem the
   22464 Präsident President
   20855 streng in strictest
   4377 geheim secrecy
   23610 eröffnen inform
   18140 comma(,) comma(,)
   22260 sobald as soon as
   5905 Kriegs war’s
   13347 Ausbruch outbreak
   20420 mit with
   39689 Vereinigten Staaten United States
   13732 fest certain
   20667 steht is
   6929 und and
   5275 Anregung suggestion
   18507 hinzufügen add
   52262 Japan Japan
   1340 von by
   22049 sich himself
   13339 aus from
   11265 zu to
   22295 sofortig immediately
   10439 beitretung join
   14814 einladen invite
   4178 (setze infinitiv mit zu—i.e., einzuladen) (form the infinitive—i.e., to invite)
   6992 und and
   8784 gleichzeitig at the same time
   7632 zwischen between
   7357 uns us
   6926 und and
   52262 Japan Japan
   11267 zu to
   21100 vermitteln mediate
   21272 stop(.) stop(.)
   9346 Bitte Please
   9559 den the
   22464 Präsident President
   15874 darauf of this
   18502 hinweisen point to
   18500 comma(,) comma(,)
   15857 dass that
   2188 rücksichtslos ruthless
   5376 Anwendung employment
   7381 unserer our
   98092 U-boote U-boats
   16127 jetzt now
   13486 Aussicht prospect
   9350 bietet offers
   9220 comma(,) comma(,)
   76036 England England
   14219 in in
   5144 wenigen few
   2831 Monat- month-
   17920 en s
   11347 zum to
   17142 Frieden peace
   11264 zu be
   7667 zwingen compelled
   7762 stop(.) stop(.)
   15099 Empfang Receipt
   9110 bestahigen acknowledge
   10482 stop(.) stop(.)
   97556 Zimmermann Zimmermann
   3569 stop(.) stop(.)
   3670 Schluss der Depesche End of dispatch
   Bernstorff
   Notes
   CHAPTER 1. A TELEGRAM WAYLAID
   Montgomery and de Grey: James, 136, names these two men as the decoders of the telegram. Facts of Montgomery’s background supplied by R. D. Whitehorn, Principal, Westminster College, Cambridge. De Grey listed in Who’s Who. Montgomery died in 1930, de Grey in 1951.
   13042 a variant of 13040: A discrepancy exists that has never been explained. The telegram itself bears the code number 13042, and Ambassador Page twice referred, in telegrams to the State Department, to “thirteen thousand forty-two” as “indicating the number of the code used” (Hendrick, iii, 333 and 345). But Eckhardt, who received the telegram in Mexico, twice referred, in telegrams to Zimmermann, to 13040. He specifically stated that the telegram “was received here in code 13040” and, when trying to account for the betrayal, suggested “code 13040 is compromised” (Hendrick, iii, 357, and James, 152). Ambassador Page also told the State Department that the code “was never use 
					     					 			d straight, but only with a great number of variations which are known to only one or two experts here” (Hendrick, iii, 344), and it is possible that 13042 indicated the code key to one of these variations.
   It has been suggested by several writers that the telegram was in an enciphered code, but this is disproved by the presence of repetitions in the code groups. There are eight cases of repetitions, and one group, 67893, the code group for “Mexico,” is repeated three times, and there are several cases of code groups differing in only one digit. Such repetitions, or near repetitions, would not occur in an enciphered code.
   Text of the Telegram: German Documents, ii, 1337.
   Incomplete version of the decoded text: Hendrick, iii, 336–37, and James, 136.
   “Blinker Hall”: Certain of Admiral Hall’s personal characteristics were told to me by Admiral James and Mrs. Hotblack; others were gathered from accounts of those who knew him, namely, Ewing, James, Sims, and others. The resemblance to Mr. Punch was noted in a London Times article reprinted in Sims.
   Not enough U-boats: Churchill, Crisis, 1916–18, i, 222. See also Crisis, 1915, chap. XIV, and Crisis, 1916–18, ii, chap. XV. Bernstorff told the postwar German Investigating Committee that his arguments against the use of unrestricted submarine warfare had prevailed in the spring and summer of 1916 only because “of the obviously insufficient number of U-boats. We had on March 1 only 35 large U-boats ready for action.” German Documents, i, 341.
   Telconia: Information supplied by Admiralty Archivist, Commander P. K. Kemp. See also Landau, 151–82.
   German transatlantic cables: Bright.
   Committee of Imperial Defense: Information supplied by Admiralty Archivist.
   Africa-Brazil cable cut by Eastern Telegraph: From A Great Seaman; the Life of Admiral Sir Henry Oliver by Admiral Sir William James (London: Methuen, 1956).
   Admiral Oliver summons Ewing: This and subsequent facts about Ewing and the early history of Room 40 are from the life of Ewing by his son, A. W. Ewing.
   Montgomery’s translation: Letter to The Times (London), October 1930, from Dr. F. C. Burkitt, Professor of Divinity, Cambridge.
   Germans ignored possibility of enemy decoding: Young.
   Decoders read German messages more quickly than recipients: Ibid.
   Magdeburg signal book: Corbett, i, 170; James, 29; Landau, Pratt.
   Captain Hall: His innovations, James, 16–17. His character and habits, James, Ewing, Hendrick, Sims.
   Iron-bound sea chest: James, 56–57.
   Alexander Szek: “The Mysterious Disappearance of Alexander Szek,” unpublished manuscript by Wildon Lloyd. See also Landau, 155–58, and Pratt.
   Wassmuss: Sykes, 62–78; Landau, 158–59.
   Anglo-Persian pipeline: Information supplied by British Petroleum Co., Ltd., formerly Anglo-Iranian Oil Co., Ltd., which states in a letter to the author, that although the tribesmen who cut the pipeline were instigated by enemy agents, “of whom there were several about, it cannot be said for certain that it was Wassmuss, nor were his capture, sometime later, and subsequent escape, connected with it.”
   “Lashed the tribesmen”: Sykes, 77.
   Hall locates code book: James, 69.
   13040 one of two codes: Hall’s affidavit, Mixed Claims Commission, Ex. 320.
   £5,500,000 a day: Dearle.
   Collapse of the allies would be a matter of months: André Tardieu wrote in France and America that if the Federal Reserve decision had been maintained, “the defeat of the Allies would have been merely a question of months” (quoted in Grattan, 175). J. M. Keynes (273, n. 1) wrote that England’s task would soon have become “entirely hopeless” without the assistance of the U.S. Treasury.
   As Churchill was to say later: “The action of the United States with its repercussions on the history of the world depended, during the awful period of Armageddon, upon the workings of this one man’s mind and spirit to the exclusion of almost every other factor; … he played a part in the fate of nations incomparably more direct and personal than any other man.” Churchill, Crisis, 1916–18, i, 234.
   CHAPTER 2. THE CLEVER KAISER AND THE YELLOW PERIL
   Die gelbe Gefahr!: According to the Spectator, December 11, 1897, the Kaiser was the first statesman to allude to the Yellow Peril in a public speech.
   Kaiser grasped significance: Writing to the Czar, September 26, 1895, the Kaiser says the danger of the Far East to Europe has been greatly on his mind, “and at last my thoughts developed in a certain form and this I sketched on paper. I worked it out with an Artist and had it engraved for public use.” Willy-Nicky letters, 16–17.
   “Christmas-tree candles …”: Ludwig, 252. Ludwig gives no date for this letter, and there appears to be some discrepancy, for the Kaiser has already described sketching the picture in his letter to the Czar of September 26, three months before Christmas.
   Knackfuss: Willy-Nicky letters, 20, n. 3.
   Kaiser’s picture: The picture is reproduced in Harper’s Weekly, January 22, 1898; also in Viereck, The Kaiser on Trial, facing 434.
   “He wanted it always to be Sunday”: Zedlitz, xv.
   Morning paper printed in gold: Daisy, Princess of Pless, 265.
   Kaiser on dynastic rulers: Kaiser to Czar, October 25, 1895; Willy-Nicky letters, 21–26.
   Kaiser’s letters written in English: Willy-Nicky letters, p. ix. Errors in English spelling: ibid., xi.
   Kaiser and Santa Margarita Islands, Venezuela: Thayer, W. R., Life and Letters of John Hay (Houghton Mifflin, 1915), ii, 284.
   Kaiser’s attempt to buy Magdalena Bay: Ambassador Choate to Secretary Hay, undated [1902]. Hay Papers, Library of Congress.
   God would choose Germany: “And so the Creator has ever kept this nation in His sight—the nation elected by Him to bestow the gift of peace at last upon the world. … That God should choose a Prussian—that must mean great things!” The Kaiser, quoted by Ludwig, 309. The Kaiser generally referred to God as his “Great Ally,” Ludwig, 317. See also chap. xviii, “Ich und Gott,” in Viereck, The Kaiser on Trial.
   “All-Highest paid his respects to the Highest”: Zedlitz.
   “The Kaiser has had another fit …”: Roosevelt to Hay, March 30, 1905; Schieber, 236.
   “I ADORE the English!”: Roosevelt to Trevelyan, October 1, 1911; Letters, Morison, vii, 396.
   Kaiser’s letters urging Czar to fight Japan: Quotations are from letter of April 16, 1895, Willy-Nicky letters, 10. See also letters of July 10, 1895, ibid., 13; September 2, 1902, ibid., 86; and Memorandum to German Diplomats, August, 1904; “This will be the decisive battle between … Western civilization and Eastern semi-civilization … the battle which I prophetically drew in my painting …” Ludwig, 254.
   Ten thousand Japanese in Mexico: December 28, 1907, Willy-Nicky letters, 218–20.
   Kaiser’s remark to Balfour: Dugdale, i, 214. The remark was made in 1899 during the Boer War on the occasion of the Kaiser’s visit to the Queen at Windsor.
   “Autocratic zigzag”: Pringle, 379.
   “A great admirer of Your Majesty …”: Dennis, 390.
   Interview with Tower: Tower to Roosevelt, January 28, 1908; Pringle, 403–404.
   Interview with Hale: Roosevelt to Elihu Root, August 8, 1908, Letters, Morison, vi, 1163–65; Roosevelt to Arthur H. Lee, October 17, 1908, ibid., 1292–94; Roosevelt to Whitelaw Reid, January 6, 1909, ibid., 1465–67.
   In his “strongest manner”: Letter to Root, cited above.
   “I wish he would not have brain storms”: Roosevelt to Whitelaw Reid, December 4, 1908, Letters, Morison, vi, 1411.
   “A tear fell on his cigar”: Daisy, Princess of Pless, 256.
   American Minister in Guatemala: Archives, 712.94/27A.
   Mexicans as racial brothers of the Japanese: Pooley.
   Admiral Yashiro’s speech: Reported by La Campana of Guatemala City, April 29, 1911, Archives, 712.94/1.
   Goltz steals secret treaty: This account of his exploit is Goltz’s own, as contained in the memoirs he wrote in 1917 whi 
					     					 			le awaiting trial as a wartime saboteur in the United States.
   Ambassador Wilson’s denial: H. L. Wilson to Secretary of State Philander C. Knox, June 13, 1911, Archives, 712.94/2. Upon publication of von der Goltz’s book in 1917, Wilson again wrote to former Secretary Knox: “That part of this story which relates to the Embassy in Mexico City and my action is pure invention. No such treaty was ever placed in my hands, nor to my knowledge in the hands of the Department of State during your administration of its affairs.” Wilson to Knox, February 19, 1918, Archives, 712.94/26.
   Ambassador Wilson scurried up to Washington: H. L. Wilson, 207.
   President Taft’s mobilization: U.S. Foreign Relations, 1911.
   Major Herwarth von Bittenfeld: N.Y. Sun, March 11, 1911.
   Texas and border states in a ferment: Ibid., March 23, 1911. Reports from Fort Sam Houston.
   Foreign capitals buzzed: Ibid., March 13, 1911. Reports from Paris and foreign press summary.
   German press: Ibid., March 18, 1911. Report from Berlin.
   Ambassador Wilson’s private report to State Department: Henry Lane Wilson to Secretary Knox, June 13, 1911, Archives, 712.94/2.
   Taft’s mobilization inspired by Mexican revolt: U.S. Foreign Relations, 1911, 422; see also Wilson, H. L., 208–11.
   CHAPTER 3. “SEIZE THE CUSTOMS HOUSE AT ONCE!”
   Madero on a white horse: O’Shaughnessy, Intimate Pages, 173.
   Madero as apostle and redeemer: Ibid., 149–60.
   Ten thousand dead: The counter-revolution, called the Dicena Tragica, is described at first hand by Wilson, H. L., 252–88, and by O’Shaughnessy, Intimate Pages, 172–91.
   Huerta’s flat nose, etc.: O’Shaughnessy, Intimate Pages, 191–93. A good portrait is in Moats, 112.
   “Sneaking admiration”: Wilson to Mrs. Hulbert, February 1, 1914, Baker, iv, 305. Huerta a “diverting brute”: Wilson to Mrs. Hulbert, August 24, 1913, ibid., 273.
   “Puritan of the North”: Wilson, H. L., 295.
   Wilson’s “clear duty”: Memorandum to foreign governments, November 1, 1913, U.S. Foreign Relations, 1913, 856.
   “Irony of fate …”: Wilson to E. G. Conklin, Baker, iv, 55.
   “That scoundrel Huerta”: Wilson to Edith G. Reid, August 15, 1913, Baker, iv, 266.
   Japan sold Huerta arms: Archives, 894.20212 passim. See also Vagts, Mexico, Europa und Amerika, 191.
   Señor de la Barra: Pooley.
   A fearful prospect: U.S. Foreign Relations, 1913, 776.