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The assassination of Archduke Franz Ferdinand triggered World War I by setting off a chain reaction of alliances and declarations of war. The act of murder by a Serbian nationalist, Gavrilo Princip, caused Austria-Hungary to issue an ultimatum to Serbia, which Austria-Hungary used as a pretext to declare war, leading Russia, Germany, France, and Britain to enter the conflict. -
The United States adopted a policy of neutrality in the lead-up to both World War I and World War II, primarily driven by a desire to avoid "entangling alliances" and the costly conflict in Europe. -
it halted Germany's advance into France, ended their hope for a quick victory in World War I, and resulted in the stalemate that led to years of trench warfare on the Western Front. It was a critical Allied victory that reshaped the course of the war and demonstrated the effectiveness of defensive strategies. -
The sinking of the RMS Lusitania on May 7, 1915, was significant because it killed 128 Americans and enraged the public, shifting American opinion against Germany and contributing to the U.S. entry into World War I in 1917. The incident highlighted the dangers of unrestricted submarine warfare to civilians and challenged then-accepted international war protocols. -
The Battle of Verdun was important for its symbolic significance to French morale, its role in the German strategy of attrition, and its immense human cost. While militarily inconclusive, it became a symbol of French resistance, and its staggering casualties—over 500,000 for France and 450,000 for Germany—had a profound psychological and political impact -
it prompted Germany to issue the Sussex Pledge, an agreement to alter its unrestricted submarine warfare and avoid sinking passenger and non-military ships without warning. This pledge temporarily appeased the United States and kept them out of World War I, but its eventual violation by Germany in 1917, leading to the resumption of unrestricted submarine warfare, was a major factor in the U.S. decision to enter the war. -
a turning point in military strategy and for its immense human cost, which became a symbol of the war's futility. It forced a reassessment of tactics, leading to better coordination between infantry and artillery, and a greater emphasis on firepower over manpower. The battle was also critical for the development of the British and Canadian armies, which used the hard-won lessons to achieve future successes. -
convincing the United States to enter World War I, fundamentally changing the course of the war. By proposing a military alliance to Mexico against the U.S., Germany revealed its hostile intentions to American leaders and the public, shifting public opinion and swaying President Woodrow Wilson to request a declaration of war. -
the practice of sinking enemy ships, both military and civilian, without warning, most notably during World War I. Visual representations include German propaganda maps showing the waters around Britain, covered in symbols for sunken ships, and photographs of German U-boats involved in these attacks. -
but iconic visuals include President Woodrow Wilson addressing a joint session of Congress, patriotic parades with soldiers marching down Fifth Avenue, and propaganda posters like "I Want You for U.S. Army," Getty Images. Images also captured the nation's military buildup, such as soldiers drilling at home or testing new equipment like tanks and aircraft, The Atlantic.