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The assassination of Archduke Franz Ferdinand was important to World War I because it triggered a chain reaction of alliances that pulled major European powers into conflict. -
American neutrality in World War I, declared by President Woodrow Wilson in 1914, was an initial policy of non-intervention in the European conflict due the desire to avoid entanglement in foreign wars, and the country's diverse ethnic makeup. However, this neutrality was compromised by economic ties favoring the Allies, German submarine warfare (including the sinking of the Lusitania), and the Zimmermann Telegram. Ultimately, these factors led the U.S. to declare war on Germany in 1917. -
The battle, and the last hope for German victory, only lasted a day and resulted in a devastating loss for the German war effort. This was a major success for Americans and the Allies as German forces were pushed away from the area of the Marne River -
The sinking of the RMS Lusitania on May 7, 1915, was significant because it killed 1,195 people, including 128 Americans, which outraged the U.S. public and fueled anti-German sentiment. This event accelerated the United States' eventual entry into World War I, shifting American public opinion away from the country's neutral stance. -
The Battle of Verdun was important because it became a symbol of French resistance and a brutal war of attrition that highlighted the horrors of trench warfare. The battle lasted for 10 months, had enormous casualties for both sides ((~500,000) for France, (~400,000) for Germany), and ended with no significant territorial gains, forcing a shift in military tactics toward less static, more coordinated offensives. -
The Sussex Incident was important because it escalated tensions between the United States and Germany during World War I and led to the short-lived but consequential "Sussex Pledge". The sinking of the Sussex, a French passenger ferry, prompted a U.S. threat to break diplomatic ties, to which Germany responded by promising to limit its use of unrestricted submarine warfare. -
The Battle of the Somme was important because it resulted in devastating casualties, highlighting the brutality of trench warfare and leading to the end of Britain's "pals battalions".