"On the 1st of February we intend to begin submarine warfare unrestricted. In spite of this, it is our intention to endeavor to keep neutral the United States of America.
"If this attempt is not successful, we propose an alliance on the following basis with Mexico: That we shall make war together and together make peace. We shall give general financial support, and it is understood that Mexico is to reconquer the lost territory in New Mexico, Texas, and Arizona. The details are left to you for settlement.
"You are instructed to inform the President of Mexico of the above in the greatest confidence as soon as it is certain that there will be an outbreak of war with the United States, and suggest that the President of Mexico, on his own initiative, should communicate with Japan suggesting adherence at once to this plan. At the same time, offer to mediate between Germany and Japan.
"Please call to the attention of the President of Mexico that the employment of ruthless submarine warfare now promises to compel England to make peace in a few months.
"Zimmerman."
The Administration was in possession of this document, and achieved a dramatic coup in exposing its contents just as important war legislation was pending in Congress. The immediate effect of the revelation was that the Armed-Ship Bill passed the House of Representatives by the overwhelming majority recorded in the previous chapter. The Senate was no less astonished; but its attitude was one of incredulity and produced a demand to the State Department vouching for the document's authenticity and demanding other information. Secretary Lansing assured it that the letter was bona fide, but declined to say more.
The letter was transmitted to Von Eckhardt through Count von Bernstorff, then German Ambassador at Washington, and now homeward bound to Germany under a safe conduct obtained from his enemies by the country against which he was plotting war. It came into the President's hands a few days before it was published on March 1, 1917, and provided a telling comment on Chancellor von Bethmann-Hollweg's declaration that the United States had placed an interpretation on the new submarine decree "never intended by Germany" and that Germany had promoted and honored friendly relations with the United States "as an heirloom from Frederick the Great." Its disclosure was viewed as a sufficing answer to the German Chancellor's plaint that the United States had "brusquely" broken off relations without giving "authentic" reasons for its action.
The bearings of the proposal to Mexico were admirably stated by the Associated Press as follows:
"The document supplies the missing link to many separate chains of circumstances which, until now, have seemed to lead to no definite point. It sheds new light upon the frequently reported but indefinable movements of the Mexican Government to couple its situation with the friction between the United States and Japan.
"It adds another chapter to the celebrated report of Jules Cambon, French Ambassador in Berlin before the war, for Germany's world-wide plans for stirring up strife on every continent where they might aid her in the struggle for world domination which she dreamed was close at hand.