On May 7, 1915, a German submarine torpedoed the British ocean liner RMS Lusitania en route from New York to England. Attacked without warning off the coast of Ireland, the ship sank in fifteen minutes, killing nearly 2,000 civilians, including 128 Americans.
Woodrow Wilson immediately denounced the sinking of the Lusitania in harsh, threatening terms, demanding that Germany pledge to never launch another attack on citizens of neutral countries, even when traveling on French or British ships. Germany acknowledged Wilson's demand, but only temporarily. In March, 1916, a German U-boat torpedoed the French passenger liner Sussex, causing a heavy loss of life and injuring several Americans.
Two months later, in what's known as the Sussex pledge, Germany announced that they would no longer sink Allied merchant ships without warning but made it clear that it would resume submarine attacks if the Allies refused to respect International Law which meant that the Allies had to lift their blockades of food and other materials bound for the Central Powers.
Despite further provocations, President Wilson still hoped for a negotiated settlement until February 1, 1917, when Germany resumed submarine warfare against merchant ships, including those of the United States and other neutral countries. In response, Wilson broke off diplomatic relations with Germany.
Then, on Feb. 25, the British intercepted and decoded a telegram from Germany's Foreign Secretary Arthur Zimmermann to the German Ambassador in Mexico. The "Zimmermann Telegram" proposed that in the event of war with the United States, Germany and Mexico would form an alliance. In return, Germany promised to regain for Mexico its "lost provinces" of Texas, Arizona, and New Mexico.
The release of the Zimmermann Telegram ignited a public furor that was further enflamed by the loss of three U.S. merchant ships to German submarines. After much thought and introspection, President Wilson appeared before a Joint Session of Congress on the evening of April 2, 1917 and asked for a Declaration of War against Germany.
This is a partial excerpt of what he said:
It is a fearful thing to lead this great peaceful people into war, into the most terrible and disastrous of all wars, civilization itself seeming to be in the balance. But the right is more precious than peace, and we shall fight for the things which we have always carried nearest our hearts - for democracy, for the right of those who submit to authority to have a voice in their own governments, for the rights and liberties of small nations, for a universal dominion of right by such a concert of free peoples as shall bring peace and safety to all nations and make the world itself at last free. To such a task we dedicate our lives and our fortunes...
Wilson was having lunch in the State Dining Room when word came that the Declaration of War had arrived for his signature. Although no one knows what Wilson ate for lunch on that momentous day, we do know that by the time the United States entered the war, German submarines were taking a catastrophic toll on the supplies of food and other provisions being shipped to Britain from abroad.
In response, the British Admiralty established a system of convoys. Under the plan, merchant ships were grouped together in convoy and provided with warship escorts through the most dangerous stretches of the North Atlantic.
The convoys had a dramatic effect. By the end of 1917, the tonnage of Allied shipping lost each month to German U-boat attacks plummeted from one million tons in April to 350,000 tons in December. And while many other factors were at play, the increase in food and other necessary provisions helped stiffen the resolve of French and British troops and thwarted Germany’s attempt to force Britain’s surrender.
