The World War had raged for nearly three years, and Germany felt the pinch with trench warfare in France, the British blockade, and bitter warfare on the icy Eastern Front. Despite the pressures against them, the German Army had been the main strength of the Central Powers and held against the Allied onslaughts. The Battle of Verdun lasted ten months over 1916 and cost 300,000 lives, ultimately ending in a failure of Germany taking Verdun, though some ground was taken. Kaiser Wilhelm II had taken it as enough to declare victory in the war and call for terms of peace.
The United States had gradually come into line with the Allies over the course of the war after being vehemently neutral due to German naval attacks and increasing economic influence due to war-profiteering in Britain while Germany sat behind its blockade. The original countermeasures to the blockade had been “unrestricted” submarine warfare against Allied ships in the Atlantic, torpedoing them at sight rather than stopping and conducting searches as was typical in naval warfare. While tactically advantageous, the sinking of the RMS Lusitania and others had resulted in grave negative response as many American passengers had been killed despite being warned against travel. The outcry from neutral countries had put an end to the U-boat attacks, but the failure of diplomacy in December of 1916 prompted the German command to resume unrestricted submarine warfare beginning February 1, 1917, though it would almost certainly bring the United States into the war.
Initially, Zimmermann had considered finding more allies such as Mexico and Japan to expand the war to soak up inevitable American troops, but he settled on ways of keeping the United States out or even voicing positive support for Germany. He sent a telegram through the ambassador to Washington reading,
“We intend to begin on the first of February unrestricted submarine warfare. We shall endeavor in spite of this to keep the United States of America neutral. While such tactics are not to our pleasure, it has become necessary to fight against the British Navy as they have sought to starve the people of Germany into submission through their blockade. Americans as well have felt the economic frustration of their activity of war. Please call the President's attention to the fact that the ruthless employment of our submarines now offers the prospect of compelling England in a few months to make peace.” Signed, ZIMMERMANN
Word of the German eagerness for peace seized many Americans, especially the German-Americans whose parents or themselves had immigrated. Other Americans began to demand the opening of German ports to ships with food and medicine, especially those whose exports had been harmed by the cut-off of German consumers. Britain had allowed searched ships through its blockade, but propaganda through political cartoons showing John Bull stealing dinner from starving German children’s mouths stirred public opinion. William Jennings Bryan, who had resigned as Secretary of State due to Wilson’s fascination with the war, spoke out from his stage on the Chautauqua circuit that the United States must take up a fresh stand to end the war before desperation pushed the Germans too far. Former President Theodore Roosevelt spoke out against the German “pirates”, but promises of German U-boat escorts for neutral ships kept their image as, at most, wartime privateers.
President Wilson delivered an address to Congress on April 6 to confirm neutrality while publically rebuking the Germans for their unrestricted submarine warfare and also rebuking the Allies for not seeking reasonable peace. Allied freight was sunk by the millions of tons in the Atlantic, and improved convoy and decoy tactics were limited by increasing neutral support for blockade-running ships with courses set for lucrative German ports. The war seemed to continue at a bitter stalemate over the summer, but the collapse of Russia and decisive Central victory at the Battle of Caporetto seemed to give the Germans an edge. As the revolutionary government of Russia began talks for peace at Brest-Litovsk, the beleaguered French also agreed to armistice with Austria through Belgian intermediaries. Frustrated Britons felt that they could not carry the war on alone and capitulated to US-led talks hosted in New York.
Diplomacy was bitter and nearly fell apart on a number of occasions as various sides made overwhelming demands. Enumerated reparations caused so much money to exchange hands that an equivalency was found granting primary gains to France, Alsace-Lorraine became divided, and Northeastern Europe became a variety of new states such as Poland, Finland, Latvia, Lithuania, and Estonia, while Austrian advances on Serbia were rebuffed and internal nationalities in the Austro-Hungarian Empire and the Ottoman Empire gained significant self-rule. Over the course of the 1920s, many of these nations would rebel to become independent states, as well as Ireland in the UK, as the Balkans and Middle East shattered into other states.
Meanwhile, Wilson would get his wishes of a League of Nations to be hosted in neutral Geneva. Upon the implosion of the Ottoman Empire, renewed colonialism would swarm into the Middle East, sparking, along with bitter economic downturn, the Second World War in the mid-1930s. Again, the United States would seek neutrality.
In reality, Zimmermann sent his telegram to Mexico, suggesting an alliance in which Germany would aid the Mexican forces with weapons and money to retake Texas, New Mexico, and Arizona territory lost in the Mexican-American War some seventy years earlier. The telegram was delivered to Americans by British code-breakers, however, and word of such treachery shocked the public as did the resumption of unrestricted submarine warfare, which would prompt an American declaration of war against Germany.