World War I: Military and Diplomacy

By the end of this lesson, students will be able to:

• Account for the chain of pressures — submarine warfare, the Lusitania sinking, the Sussex Pledge, the Zimmermann Telegram, and the February 1917 Russian Revolution — that ended American neutrality between 1914 and April 1917.
• Analyze Wilson's April 2, 1917 war message and the rhetorical claim that the world must be made safe for democracy.
• Describe the contribution of the American Expeditionary Force under General John Pershing at Belleau Wood, Saint-Mihiel, and the Meuse-Argonne offensive between late 1917 and the November 11, 1918 armistice.
• Identify the major proposals in Wilson's January 1918 Fourteen Points address, including open diplomacy, freedom of the seas, self-determination, and the League of Nations.
• Account for the Senate's rejection of the Treaty of Versailles, including Henry Cabot Lodge's reservations, Wilson's October 1919 stroke, and the consequences for the postwar international order.
• Use Skill 2.C (Sourcing and Situation) to analyze the Zimmermann Telegram and the Wilson war message inside the diplomatic situation that produced each document.

When the European great powers went to war in August 1914, President Woodrow Wilson issued a formal declaration of neutrality and asked Americans to be neutral in thought as well as in action. The country's foreign-policy tradition since George Washington's farewell address had counseled against entangling alliances with the European powers, and Wilson's instinct, like that of most of his predecessors, was to keep the country out of a war whose outbreak the State Department had not foreseen and whose stakes for the United States seemed remote. That neutrality lasted thirty-two months and broke under three converging pressures (KC-7.3.II.A).

The first pressure was submarine warfare. Germany's surface fleet was bottled up in port by the British naval blockade, leaving the U-boat as Berlin's only practical weapon against Allied shipping. On May 7, 1915, a German submarine torpedoed the British ocean liner Lusitania off the south coast of Ireland; the ship sank in eighteen minutes, taking roughly twelve hundred lives, including one hundred twenty-eight Americans. Wilson protested in three diplomatic notes drafted with help from Secretary of State William Jennings Bryan, who resigned over the second note's tone, and Germany temporarily restricted submarine attacks on passenger ships under the so-called Sussex Pledge of May 1916. The pledge held until February 1, 1917, when the German general staff, calculating that unrestricted submarine warfare could starve Britain into surrender before American intervention could matter, ordered U-boats to sink any vessel approaching Allied ports without warning. American merchant losses mounted within weeks.

The second pressure was the Zimmermann Telegram. In January 1917, German Foreign Minister Arthur Zimmermann sent a coded cable to the German minister in Mexico City proposing that, in the event the United States entered the war, Germany would support a Mexican military campaign to recover Texas, New Mexico, and Arizona. British naval intelligence intercepted and decoded the telegram, then waited until late February to release it through diplomatic channels in a way that concealed the British signals-intelligence operation. American newspapers printed the text on March 1, 1917; Zimmermann himself confirmed its authenticity three days later in Berlin. Public opinion in the western states, where antiwar sentiment had been strongest, shifted decisively. The third pressure came two weeks later, when the February 1917 Russian Revolution forced the abdication of Czar Nicholas II and replaced the autocratic Romanov government with a provisional liberal coalition. The revolution removed the political embarrassment of allying the United States with one of the most repressive monarchies in Europe and let Wilson cast the war as a contest between democracies and autocracies.

On April 2, 1917, Wilson asked a joint session of Congress for a declaration of war. The address contained the line that has organized American memory of the conflict ever since: the world, Wilson argued, must be made safe for democracy. Congress voted four days later, with six senators and fifty representatives opposed, including Jeannette Rankin of Montana, the first woman elected to Congress. The country's foreign-policy tradition of staying out of European affairs had been broken (KC-7.3.II.A).

The military contribution that followed was real but compressed. Under General John Pershing, the American Expeditionary Force grew from a few thousand troops in France in summer 1917 to roughly two million by the November 1918 armistice. Pershing insisted that the AEF fight as an independent American army rather than be parceled out as replacements into French and British divisions, a decision that delayed full American combat participation but preserved the political weight of an autonomous American contribution. The first significant engagement came in early June 1918 at Belleau Wood and Chateau-Thierry, where U.S. Marines and Army units helped halt the final German spring offensive northeast of Paris. In September the AEF reduced the Saint-Mihiel salient in its first independent offensive operation. The forty-seven-day Meuse-Argonne offensive, which began September 26, 1918, was the largest American military operation up to that point in U.S. history; it pushed German forces back toward the Rhine and helped force Germany to seek armistice terms. The CED records that the AEF played a relatively limited combat role compared with the European belligerents who had been fighting since 1914, but its arrival in fresh and growing numbers tipped the balance of the war toward the Allies (KC-7.3.II.B). Fighting ended at the eleventh hour of the eleventh day of the eleventh month of 1918.

Wilson had spent the last year of the war preparing the American case for the postwar settlement. On January 8, 1918, in an address to a joint session of Congress, he set out the Fourteen Points, a list of war aims drafted with help from a private group of academic advisers known as the Inquiry. The first five points called for open diplomacy in place of secret treaties, freedom of the seas, removal of economic barriers among nations, reduction of armaments, and an impartial adjustment of colonial claims with regard for the inhabitants. Most of the remaining points proposed specific territorial settlements in Europe, including self-determination for the peoples of the Austro-Hungarian and Ottoman empires. The fourteenth and most consequential point called for a general association of nations, the League of Nations, that would guarantee political independence and territorial integrity. Wilson sailed for France in December 1918 as the only head of state in attendance at the Paris Peace Conference, an unprecedented step that critics at home read as evidence that he intended to negotiate the peace personally and present the Senate with a finished document.

The conference that opened in January 1919 stripped most of the Fourteen Points out of the final text. British Prime Minister David Lloyd George had won a December 1918 election on the promise to make Germany pay; French Premier Georges Clemenceau wanted territorial guarantees against any future German invasion; Italian Premier Vittorio Orlando wanted the Adriatic territories Italy had been promised in the 1915 Treaty of London. The Treaty of Versailles, signed in the Hall of Mirrors on June 28, 1919, imposed punitive terms on Germany. Article 231, the war-guilt clause, required Germany to accept sole responsibility for causing the war. Germany was stripped of all overseas colonies, lost Alsace-Lorraine to France, lost territory to the new Polish state, was barred from union with Austria, and had its army limited to one hundred thousand men. A separate reparations commission later set the German bill at one hundred thirty-two billion gold marks. The fourteenth point survived as Article X of the League Covenant, which committed members to defend one another against external aggression.

Wilson's defeat at home was the more consequential of his two failures. Senate Foreign Relations Committee chairman Henry Cabot Lodge, a Massachusetts Republican who had opposed Wilson on partisan and substantive grounds for two decades, drafted fourteen reservations to the treaty, most of them aimed at Article X. The reservations sought to protect congressional war-declaration powers, to preserve the Monroe Doctrine, and to keep the United States free to leave the League at any time. Wilson rejected the reservations as evisceration and refused to compromise. In September 1919 he set out on a national speaking tour to rally public opinion; on September 25, after a speech in Pueblo, Colorado, he collapsed, and on October 2 he suffered a major stroke that left him partially paralyzed and unable to govern effectively. His wife Edith and his physician concealed the severity of the stroke from the cabinet for the remainder of his term. The Senate voted twice on the treaty: in November 1919 with the Lodge reservations attached, and in March 1920 in modified form. Wilson, immobilized in the White House, instructed Senate Democrats to vote against any version that included the reservations. Both votes failed to reach the required two-thirds majority. The United States signed a separate peace with Germany in 1921 under President Warren Harding and never joined the League of Nations (KC-7.3.II.C). Topic 7.11 takes up the interwar foreign-policy pattern that followed; Topic 7.12 takes up the second American break with neutrality after Pearl Harbor in 1941.

The four excerpts below are the diplomatic and rhetorical hinge points of the lesson: the documentary trigger that broke American neutrality, the speech that defended the war, the address that set out the postwar vision, and the treaty that buried most of it.

1. (Causation) Rank the three main pressures that ended American neutrality between 1914 and April 1917 — submarine warfare, the Zimmermann Telegram, and the February 1917 Russian Revolution — from most to least decisive. Defend the ranking with at least two pieces of specific evidence.
2. (Sourcing and Situation) Read the Zimmermann Telegram alongside Wilson's April 2, 1917 war message. How does each document fit into the diplomatic situation that produced it, and what does the contrast in tone, audience, and purpose reveal about the road to war?
3. (Continuity and Change) Compare Wilson's neutrality message of August 1914 with his war message of April 1917. Identify two continuities and one significant shift in the way each defines the country's interest in the European conflict.
4. (Causation) Account for the failure of the Treaty of Versailles in the U.S. Senate. Which of the following bears the most responsibility, and why: Henry Cabot Lodge's reservations, Wilson's October 1919 stroke, the constitutional structure of the treaty-ratification process, or the substance of Article X itself?
5. (Comparison) Compare Wilson's Fourteen Points with the final text of the Treaty of Versailles. Identify two points that survived in some form and two that were stripped out. What does the gap between aim and outcome reveal about American influence at the Paris Peace Conference?

Draft alignment — pending educator review. AP USH codes correspond to the official College Board Course and Exam Description (Effective Fall 2023, Version 1). Statements below are paraphrased in the CountryReports voice; refer to the College Board's published CED for verbatim wording.