One hundred years ago, on Feb. 26, 1917, President Woodrow Wilson learned about the telegram that would pull the U.S. into World War I. The Zimmermann Telegram—a secret offer by Germany to help Mexico reconquer the American Southwest—not only compelled Washington to end a tradition of neutrality, but transformed the balance of world power for the next century. It’s a historical episode with important lessons as President Trump contemplates how to conduct international politics in the 21st century.
In 1914 Germany had launched its U-boat campaign, using submarines to sink ships without warning, including those from neutral nations. In May 1915 a German sub torpedoed a British civilian liner, the Lusitania, killing 128 Americans. Wilson threatened military action if it happened again, which forced Germany to impose restrictions on its U-boats.
As the war ground on, however, Germany began to view submarine warfare as its route to victory. By 1917 the German high command believed it could bring Britain and France to their knees in six months by sinking neutral ships and depriving the Allies of food and supplies. Yet the Germans knew this would arouse the ire of Wilson, who had won re-election only months earlier, running on the slogan “he kept us out of war.”
How to counter America’s potential response? On Jan. 19, 1917, Germany’s foreign minister, Arthur Zimmermann, sent a coded telegram to his ambassador in Mexico. The ambassador was instructed to offer the Mexican president, Venustiano Carranza, an alliance: If America entered the war, Germany proposed that Mexico open a second front against the U.S. The Germans would then help “regain by conquest her lost territory in Texas, Arizona and New Mexico.”
In some ways, it was a clever move. Carranza was still smarting from President Wilson’s decision three years earlier to send an American force to occupy Veracruz, as well as Gen. John J. Pershing’s 1916 expedition against the bandit Pancho Villa. If there was a country in the Western Hemisphere ready to ally with Germany against the U.S., it was Mexico.
But if anything was set to turn American public opinion against neutrality, it was a secret plan to invade the U.S. The British, who had intercepted the diplomatic cable, knew this. So once they had fully decoded the Zimmermann Telegram, they made sure it landed on Wilson’s desk. They gave it to the U.S. ambassador in London on Feb. 24.
When Wilson released it to the public, the telegram rallied patriotic sentiment like nothing since the burning of the White House during the War of 1812. Yet the president remained hesitant. He still believed American neutrality was the best way to promote peace. Even after Zimmermann confirmed the authenticity of the message on March 3, Wilson waited nearly a month before asking for a declaration of war.