On April 2, 1917, a pivotal moment in global history unfolded as President Woodrow Wilson addressed a joint session of Congress, calling for a declaration of war against Germany. This decision marked the United States’ entry into World War I, a conflict that had been raging in Europe for years. Wilson’s request was not made lightly, citing critical reasons such as Germany’s abandonment of promises regarding submarine warfare in the Atlantic and Mediterranean, and its clandestine attempts to form an alliance with Mexico against the U.S. Two days later, Congress approved the declaration, officially drawing America into the Great War. Later that year, on December 7, 1917, the U.S. also declared war on Germany’s ally, Austria-Hungary. But why did the U.S. enter World War 1 at this juncture? The answer is multifaceted, rooted in shifting international dynamics and escalating provocations.
Germany’s Unrestricted Submarine Warfare: A Breach of Trust
The resurgence of German submarine attacks on passenger and merchant vessels in 1917 stands out as the primary catalyst for the U.S. decision to engage in World War I. Earlier, in March 1916, the sinking of the French ship Sussex in the English Channel, an unarmed vessel, had prompted a firm response from President Wilson. He threatened to sever diplomatic ties with Germany unless it pledged to stop attacking passenger ships and ensure the safety of crews on merchant ships before any attacks. This diplomatic pressure led to the “Sussex pledge” on May 4, 1916, where Germany agreed to Wilson’s terms.
However, by January 1917, Germany’s strategic calculations had drastically changed. German naval commanders, during a crucial wartime conference, convinced their military leaders, including Kaiser Wilhelm II, that resuming unrestricted submarine warfare could cripple Great Britain within a mere five months. They reasoned that despite the “Sussex pledge,” the United States had already forfeited its neutral status by significantly aiding the Allies with munitions and financial support. Furthermore, they argued that America had implicitly endorsed the Allied blockade against Germany, thus justifying a more aggressive naval strategy.
Despite strong objections from German Chancellor Theobald von Bethmann-Hollweg, who foresaw that this action would inevitably draw the United States into the war and ultimately lead to Germany’s defeat, the German government proceeded with its plan. They gambled that their U-boats could secure a swift victory before American troops could effectively mobilize and reach Europe. Consequently, on January 31, 1917, the German Ambassador in Washington, Count Johann von Bernstorff, informed U.S. Secretary of State Robert Lansing of Germany’s intent to recommence unrestricted submarine warfare from the following day.
Stunned by this abrupt reversal, President Wilson addressed Congress on February 3, announcing the severance of diplomatic relations with Germany. Yet, he stopped short of requesting a war declaration, still uncertain if American public opinion would support such a drastic measure without irrefutable evidence of Germany’s direct threat to U.S. interests. Wilson maintained a tentative openness to negotiation, contingent on Germany ceasing attacks on U.S. shipping. However, throughout February and March 1917, German submarines relentlessly targeted and sank multiple U.S. vessels, resulting in the tragic deaths of American citizens and seamen.
The Zimmermann Telegram: A Direct Threat to U.S. Security
While grappling with the submarine crisis, President Wilson also had to confront another significant provocation: Germany’s clandestine attempt to forge a secret alliance with Mexico. On January 19, 1917, British naval intelligence intercepted and decoded a telegram dispatched by German Foreign Minister Arthur Zimmermann to the German Ambassador in Mexico City. This communication, famously known as the “Zimmermann Telegram,” proposed a deal to the Mexican government: in exchange for Mexican support in the war against the United States, Germany promised to help Mexico reclaim territories lost to the U.S. during the Mexican-American War, including Texas, New Mexico, and Arizona.
Initially, British authorities hesitated to disclose the Zimmermann Telegram to the U.S., fearing it would reveal their code-breaking capabilities to the Germans. However, with Germany’s resumption of unrestricted submarine warfare in February, the British recognized the telegram’s potential to galvanize U.S. public and official sentiment in favor of war. The intercepted telegram was finally handed over to President Wilson on February 24, and the explosive news dominated the American press the following week.
Despite the outrage sparked by the Zimmermann Telegram, Wilson still proceeded cautiously, delaying a call for war. It wasn’t until March 20 that he convened his Cabinet to formally discuss the matter – nearly a month after first learning of the telegram. Historians continue to debate the precise weight of different factors in Wilson’s ultimate decision for war in 1917, especially considering his previous reluctance to enter the conflict in 1915 after the sinking of the Lusitania and Arabic, British passenger liners that resulted in the deaths of 131 U.S. citizens.
Shifting Tides: Public Opinion and the Irreversible Path to War
By 1917, the combination of relentless submarine attacks on U.S. merchant and passenger ships, coupled with the alarming implications of the Zimmermann Telegram, fundamentally shifted U.S. public opinion. The idea of war, once distant and undesirable, became increasingly palatable, even necessary, in the eyes of many Americans. Germany’s actions were perceived as direct affronts to U.S. sovereignty and security, demanding a forceful response.
Furthermore, international law at the time suggested that arming U.S. merchant ships with naval personnel to defend against submarines could be construed as an act of war against Germany. Germany’s leadership, through their policies and actions, had conveyed a clear lack of interest in pursuing a peaceful resolution to the escalating conflict. These converging factors – the repeated violations of U.S. neutrality on the seas, the perceived threat from the Zimmermann Telegram, and the hardening of public sentiment – collectively propelled President Wilson to seek a declaration of war against Germany. Congress, reflecting the nation’s changed mood, ultimately granted Wilson’s request, marking the United States’ definitive entry into the global conflict of World War I. In essence, why the US joined World War 1 boils down to a response to direct threats and a changing understanding of America’s role in a world at war.
