US Entry into the War (AQA A-Level History): Revision Notes

US Entry into the War

Wilson's evolving position on neutrality

When the First World War began in 1914, President Woodrow Wilson maintained that American neutrality served the nation's interests. He believed that remaining outside the conflict would preserve US credibility and respect among all warring nations, positioning America to broker a peace settlement. Wilson's thinking, however, gradually shifted between 1914 and 1917. He came to recognise that genuine American influence over the post-war settlement would require direct involvement in the conflict itself. By speaking of a post-war international order even before the USA entered the war, Wilson demonstrated that his commitment to neutrality was weakening as his ambitions for reshaping global politics grew stronger.

Wilson's vision for a lasting peace

Early peace principles

As early as 1912, Wilson had articulated four principles he considered necessary for the survival of humanity and the prevention of future conflicts:

These ideas reflected Wilson's conviction that the old diplomatic system, based on secret alliances and balance-of-power politics, had failed catastrophically.

The Peace Without Victory speech

In May 1916, Wilson delivered a major address outlining the conditions necessary for enduring peace. He argued that any settlement imposed by victors upon the defeated would breed resentment and instability. Peace Without Victory describes Wilson's concept that only a negotiated settlement between equals, not a dictated peace following military triumph, could establish lasting international stability. Wilson insisted that genuine peace required equality between nations and shared participation in maintaining a new international order. He maintained that the psychological relationship between states mattered as much as territorial or political arrangements. Without mutual respect and a sense of justice, no settlement of disputed territories or national boundaries could endure.

French Premier Georges Clemenceau responded to this speech by remarking that never before had any political assembly heard such an inspiring vision of what humanity might achieve. Wilson was formulating what would become his Fourteen Points, a framework for international relations based on transparent diplomacy, self-determination, and collective security. He believed this approach would set a new standard for how nations conducted their affairs.

Failed peace initiatives

Despite Wilson's grand vision, his practical efforts to broker peace achieved nothing. Recognising that continued war threatened his plans, Wilson dispatched Colonel Edward House to Europe twice, in 1915 and 1916, to negotiate a truce. Neither mission succeeded. The belligerent powers showed little enthusiasm for American mediation. By April 1917, Wilson understood that if the USA remained neutral and the Allies negotiated peace without American participation, his influence over the post-war settlement would vanish. Only as a belligerent could the USA shape the peace.

Reasons for US entry into the war

On 6 April 1917, the United States declared war on Germany. Multiple factors contributed to this decision.

Resumption of unrestricted submarine warfare

On 31 January 1917, Germany announced it would sink any vessel found within a designated war zone around British waters, giving just eight hours' notice. The German government calculated that Britain could be starved into submission through an intensified U-boat campaign before American entry could affect the outcome. If the USA did declare war, Germany gambled that the Allies, already short of food and war materials imported from America, would surrender before US forces could cross the Atlantic in sufficient numbers.

Wilson privately considered Kaiser Wilhelm II unstable, and on 3 February 1917 broke off diplomatic relations with Germany. He still hoped to avoid war. During February and March 1917, however, German U-boats sank several American ships. These attacks made continued neutrality politically impossible.

German activities within the USA

Wilson distrusted many German-Americans, suspecting them of espionage and sabotage. Evidence suggested that German agents were indeed conducting intelligence operations within the United States. While the scale of these activities may have been exaggerated, their existence fuelled anti-German sentiment.

The Zimmerman Telegram

The Zimmerman Telegram was a coded communication from German Foreign Secretary Arthur Zimmermann to the German Ambassador in Mexico, Heinrich von Eckhart, sent on 16 January 1917. It proposed that if the USA entered the war alongside Britain and France, Mexico should form a secret alliance with Germany. In return, Germany would support Mexican efforts to reclaim Texas, Arizona, and New Mexico. In February 1917, the US Ambassador in Britain transmitted to the State Department an intercept of this telegram. The German Ambassador in Mexico had not acted on the instruction, and Mexico had no serious intention of attacking the USA. Nevertheless, Wilson used this telegram as evidence of German hostility and bad faith. It provided him with a concrete justification for war.

Declaration of war

In April 1917, Wilson asked Congress for authority to declare war on Germany. He acknowledged that he had little real choice. The USA had been provoked beyond what its credibility could tolerate. The Allies faced potential defeat. By January and March 1917, 1 million tons of Allied shipping had been sunk by U-boats. Wilson feared that without American involvement, Allied defeat was increasingly probable. More importantly, he now understood that only belligerents (countries actively engaged in warfare) could possibly influence the post-war settlement. His idealistic vision for a new international order required American participation in the conflict.

Historiographical interpretations

Historians have offered competing explanations for why the USA entered the First World War, reflecting different perspectives on Wilson's motivations and the forces that shaped his decision.

The economic and isolationist debate

During the inter-war period (1918–1941), when disillusionment with the First World War ran deep, several commentators argued that economic interests had driven American entry. C. Hartley Grattan and Walter Mills portrayed Wilson as someone manipulated by powerful business interests, including bankers and munitions manufacturers. These groups, they argued, wanted war because it would protect their enormous profits. They cited evidence showing that exports to the Allies had pulled the USA out of the 1914 Depression. Secretary of State William Jennings Bryan had resigned because he believed that loans and exports to the Allies compromised American neutrality. Charles Beard developed this argument further, emphasising that pressure for war came from ordinary business interests seeking to maintain their markets.

Many of these historians supported isolationism during the 1920s and 1930s. They deployed their economic interpretation to argue that entry into the First World War had been a mistake, and that the USA should avoid repeating it. Given the subsequent rise of Nazi Germany and American entry into the Second World War, these arguments lost credibility. More recently, however, historians such as Benjamin O. Fordham have reconsidered the economic interpretation using more sophisticated data. Fordham notes that US exports doubled as a percentage of GNP (Gross National Product: the total value of all final goods and services produced within a nation in a particular year) between 1914 and 1916, and that 70 per cent of these exports went to Europe. Within this context, the German renewal of unrestricted submarine warfare posed a genuine threat to American prosperity.

Nevertheless, most historians no longer consider economic motives decisive. By 1916, the US economy had grown so robust through supplying markets vacated by the belligerents that even if Allied trade had been completely severed, American prosperity would not have suffered substantially.

The moral crusade

President Wilson himself insisted that self-interest played no part in his decision. Since the mid-twentieth century, historians have explored different moral and ideological dimensions of American entry.

Carl N. Deger, writing in the 1950s, argued that Wilson's primary motive was legalistic (following the letter of the law). Wilson's understanding of neutrality derived from established international law, which guaranteed the USA's right to trade non-contraband goods with any belligerent. American citizens should be safe travelling on any ships. Wilson regarded unrestricted submarine warfare as illegal under international law and, indeed, a crime against humanity.

Harold Evans, writing in the 1990s, argued that Wilson acted from moral principle rather than legal technicality. He believed that the USA needed to fight in order to create a better world. Evans contrasted Wilson with Theodore Roosevelt, suggesting that Roosevelt would have entered the war earlier to defeat the aggressor Germany, address American grievances, and restore the balance of power. Wilson, however, went to war to dismantle the old system of diplomacy and establish a new international order based on rights and respect for all peoples.

Ross Kennedy, writing in 2008, developed this interpretation. He argued that Wilson blamed the old European reliance on balance-of-power politics for causing the war's military expansion. Wilson recognised, however, that the collective security he favoured could only function if nations trusted one another. He believed particularly that Germany must return the territories it had seized and establish democratic governance before it could be trusted to maintain peace. Therefore, Wilson shared the Allied war aims. Kennedy notes that there had always been a contradiction in Wilson's earlier neutrality policy because he privately favoured the Allies over Germany.

Hugh Brogan, writing in the 1960s, argued that the Germans left Wilson no alternative but war. He suggested that Wilson's professed neutrality had never been genuine, and that eventual American involvement was inevitable. The actual timing of entry, Brogan argued, lay with Germany. In February 1917, Germany took the calculated risk of resuming unrestricted submarine warfare, hoping to defeat Britain and France before the USA could mobilise. This gamble failed. Once the USA entered the conflict, its aims expanded. It was fighting for a better world where war would no longer occur, rather than simply to defeat Germany and its allies. Brogan noted that the USA did not necessarily share all the Allies' specific war aims. One contemporary editor argued that the Allies were thieves and the Germans murderers, and that Americans preferred the thieves only as the lesser of two evils.

Niall Ferguson, whose book Colossus appeared in 2003, argued that Wilson was an idealist who sought to establish an entirely new international order based on fairness and justice for all peoples. As early as December 1914, Wilson had insisted that any peace settlement should benefit all European nations equally, not impose governmental structures on alien peoples. In May 1915, he went further, declaring that every nation had the right to choose the form of sovereignty under which it would live. While the sinking of the Lusitania and unrestricted submarine warfare were undoubtedly triggers, Wilson's deeper motivation when he declared war was more elevated and ambitious.

The USA during the war

The war economy

The USA entered the war unprepared for massive industrial war production, unlike its readiness for the Second World War. The gigantic Hog Island Shipyard in Philadelphia employed 3,400 workers but failed to complete its first vessel before the war ended. Of the 8.8 million artillery rounds fired by US troops, fewer than 8,000 had been manufactured in the USA. Nevertheless, the economy was sufficiently robust to support the war effort.

Paying for the war

The war cost $33.5 billion, in addition to the $7 billion the USA lent to the Allies, which was expected to be repaid after the conflict. Two-thirds of this expenditure was raised through loans. War bonds (debt securities issued by a government to finance military operations and other expenditure in times of war) were marketed aggressively to the American public. There were five bond drives between April 1917, when the USA joined the war, and April 1919, six months after it ended. These Liberty and Victory Loans proved highly successful. Film stars such as Charlie Chaplin, Mary Pickford, and Douglas Fairbanks Jnr were deployed to encourage bond purchases. The Army Signal Corps organised aerial displays during drives in particular locations. For the third loan issue in April 1918, the country was covered with bills and posters; 9 million posters and 5 million window stickers were distributed. The government employed extensive propaganda to ensure popular financial support for the war.

Mobilisation

Mobilisation means gearing the country for war, including recruiting, equipping, and transporting the military. Having entered the war reluctantly, Wilson oversaw an effective mobilisation programme both for the military effort itself and to unite Americans in supporting it. American armed forces played a substantial role in the conflict, and the war accelerated significant changes within American society.