World War I

World War I commenced due to Gavrilo Princip assassinating Franz Ferdiand in June 28, 1914. Later in July 28, Austria-Hungary declared war on Serbia. Following suit, Germany declared war on France in August 1914. The United States remained isolated from the war until April 6, 1917 when German Submarine sank the Lusitania, killing 128 American soldiers. But the major event that caused the United States to enter World War I was the Zimmerman note that entailed Germany’s intention to provoke Mexico to cause war against the United States. On November 11, 1918, Germany formally surrendered and peace terms were negotiated.