The Wilsonian Persuasion in American Foreign Policy By Matthew C ...

Any vessel approaching Great Britain or Western Europe would be destroyed, without regard for the lives of its passengers.²⁶ The resumption of unrestricted submarine warfare would prove to be one of the great miscalculations of military history.

With the public now solidly in support, President Wilson—only months earlier elected on the slogan: “He kept us out of the war”—severed diplomatic relations with Germany, on February 3, 1917. A few weeks earlier, British intelligence had intercepted a coded message from Arthur Zimmerman, newly appointed as Germany’s Foreign Secretary, to the German Ambassador in Mexico. In it, Zimmerman outlined a plan to induce Mexico to enter the war against the United States. On February 28, the Zimmerman telegram was released to the American public, further inciting an already incensed people. Asked by a newspaper reporter in Berlin if he denied the story, Zimmerman snapped, “I cannot deny it. It is true.” In March four more American merchant vessels were sunk.

On April 2, 1917, President Wilson spoke before a joint session of the United States Congress to request a declaration of war against Germany. America’s attempt at armed neutrality had proved “ineffectual,” he said. Germany had demonstrated itself to be a threat to principles of international comity and to democracy, and must be opposed. America must fight “for the ultimate peace of the world and the liberation of its peoples. The world must be made safe for democracy.” In doing so, America sought nothing for itself, but only to play its role in the “concert of free peoples.” “To such a task we can dedicate our lives and our fortunes, everything that we are and everything that we have, with the pride of those who know that the day has come when America is privileged to spend her blood and her might for the principles that gave her birth and happiness and the peace which she has treasured.”

Within a few days, the Congress had voted for a declaration of war (by a vote of 82–6 in the Senate; 373–50 in the House); and over the following weeks, with public opinion now manifestly in support, public leaders began proclaiming that they had, from the beginning, supported intervention in response to the aggression against France and Belgium.