US Joins the First World War (AQA GCSE History)

US joins the First World War - Timeline & Summary

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At the start of the First World War, the United States remained neutral, following a policy of isolationism to avoid being drawn into European conflicts. Despite this, the US supported the Allies by trading goods, selling weapons, and providing loans. This boosted the Allied war effort.

American neutrality was tested as Germany's 'unrestricted submarine warfare' targeted ships trading with the Allies. The sinking of the RMS Lusitania in 1915, which killed 128 Americans, caused outrage but did not immediately bring the US into the war. In 1917, Germany resumed 'unrestricted submarine warfare', further provoking the US. Around the same time, the Zimmermann Telegram, in which Germany encouraged Mexico to attack the US, was intercepted. This further turned American opinion against Germany.

Russia’s exit from the war in 1917, following the Russian Revolution, allowed Germany to focus on the Western Front. This increased the pressure on the Allies. In response, the US declared war on Germany in April 1917, providing fresh troops, resources, and morale to the Allied cause.

Why did the USA avoid joining the First World War?

• When the First World War broke out in 1914 the US were neutral

  • America was going through a period of isolationism

    • This stopped them from being involved in any European war

• The American public did not want to become involved in a war in Europe

  • Many believed that America was far away from Europe and the war did not affect them

  • In 1914, 10% of Americans identified as having German heritage

  • America's economy was thriving

    • America provided supplies to the Allies and created jobs and new industries which made many people rich

• Although the US remained neutral, it was connected with the war, as America provided the Allies with:

  • loans

    • America loaned approximately $2 billion to Britain

  • supplies such as:

    • food

    • raw materials

    • weapons

    • machinery

• Before 1917, over 100,000 Americans volunteered in the First World War

Why did the USA join the war in 1917?

The sinking of the RMS Lusitania

• The USA started to become more sympathetic to joining the war effort after the sinking of the RMS Lusitania in May 1915

• Germany was attacking ships entering British waters as a part of their 'unrestricted submarine warfare'

  • Germany was attacking US ships entering British waters

• The RMS Lusitania was a passenger liner sailing from New York to Liverpool

  • German U-boats sank the Lusitania which carried over 1,000 passengers

    • There were 128 American passengers

• The sinking of the RMS Lusitania created tension between the US and Germany

  • Many Americans called for President Woodrow Wilson to declare war on Germany

    • Wilson refused

  • Germany reduced the number of U-boat attacks after the sinking of the RMS Lusitania

    • However, this ended in 1917 when Germany increased its U-boat attacks and sunk eight American ships

    • America started to increase its military funding

The Zimmermann Telegram

• In March 1917, a German secret alliance with Mexico was discovered by the US

  • The Zimmermann Telegram was intercepted by British cryptographers

    • It stated that Germany would give Mexico money and weapons to attack and take the states of Texas, Arizona and New Mexico

• This was the final straw for America, and they declared war on Germany in April 1917

Impact of US entry into the First World War

• America's entry into the First World War had a significant impact on the Allies

  • The Allies were uncertain of Russia's continuation in the war, which would have been disastrous for the Allies

    • When America joined the war, the Russian Tsar was forced to abdicate and another Revolution seemed likely

    • America joining the war effort would help to replace Russia, if and when they left the war

  • America's supplies of soldiers, oil, coal, food, weaponry and machinery were desperately needed by the Allies

    • However, it did take months for American soldiers to arrive on the front lines

• The US declaration of war was devastating for Germany

  • Although they were no longer fighting a war on two fronts since the exit of Russia, the US posed a significant threat to German victory on the Western Front

    • Therefore, Germany decided to launch an attack on the Western Front before the full strength of the American Army joined Britain and France on the Western Front