History for the day

Rico says one of the things cluttering up his filing cabinets is a copy of a portion of a book, The Zimmerman Telegram, about that odd little piece of history:

The Zimmermann Telegram (or Zimmermann Note; German: Zimmermann-Depesche; Spanish: Telegrama Zimmermann) was a coded telegram dispatched by the Foreign Secretary of the German Empire, Arthur Zimmermann, on 16 January 1917, to the German ambassador in Washington, Johann von Bernstorff, at the height of World War One. On 19 January, Bernstorff, per Zimmermann's request, forwarded the telegram to the German ambassador in Mexico, Heinrich von Eckardt. Zimmermann sent the telegram in anticipation of the resumption of unrestricted submarine warfare by the German Empire on 1 February, an act which German chancellor Bethmann-Hollweg feared would draw the neutral United States into war on the side of the Allies. The Telegram instructed Ambassador Eckardt that, if the United States appeared likely to enter the war, he was to approach the Mexican government with a proposal for a military alliance. He was to offer Mexico material aid in the reclamation of territory lost during the Mexican-American War, specifically the American states of Texas, New Mexico, and Arizona. Eckardt was also instructed to urge Mexico to help broker an alliance between Germany and Japan.

The Zimmermann Telegram was intercepted and decoded by the British cryptographers of Room 40. The revelation of its contents in the American press on 1 March caused public outrage that contributed to the United States' declaration of war against Germany and its allies on 6 April.

The text of the telegram:

On the first of February, we intend to begin unrestricted submarine warfare. In spite of this, it is our intention to endeavor to keep the United States of America neutral. In the event of this not succeeding, we propose an alliance on the following basis with Mexico: That we shall make war together and make peace together. We shall give generous financial support, and an understanding on our part that Mexico is to reconquer the lost territory in New Mexico, Texas, and Arizona. The details of settlement are left to you. 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, on his own initiative, invite Japan to immediate adherence with this plan; at the same time, offer to mediate between Japan and ourselves. Please call to the attention of the President that the ruthless employment of our submarines now offers the prospect of compelling England to make peace in a few months.

Mexican President Venustiano Carranza assigned a general to assess the feasibility of a Mexican takeover of their former territories. The general concluded that it would not be possible or even desirable for the following reasons:

Attempting to re-take the former territories would mean certain war with the United States.
No matter how "generous" it was, Germany's "financial support" would be worthless. Mexico could not use it to acquire arms, ammunition, or other war supplies, because the United States was the only sizable arms manufacturer in the Americas. The Royal Navy controlled the Atlantic sea lanes, so Germany could not possibly supply any quantity of arms.
Even if Mexico had the military means to re-take the territory, it would have had severe difficulty accommodating and/or pacifying the large English-speaking population.
Mexico had even cooperated with the ABC nations to prevent a war with the United States, generally improving relations. If Mexico were to enter war against USA it would strain relations with ABC nations—who would later declare war on Germany.

Carranza formally declined Zimmermann's proposals on 14 April, by which time the United States had declared war on Germany.
_____________________
Rico says that, in case you haven't noticed, the Mexicans took a longer-term strategy; the green on the map would cover most of the Lower 48 these days...