World War I: German submarine U-20 sinks RMS Lusitania, killing 1,199 people, including 128 Americans. Public reaction to the sinking turns many former pro-Germans in the United States against the German Empire.

World War I, or the First World War, also known as the Great War, was a global conflict between two coalitions: the Allies and the Central Powers. Major theatres of war included Europe and the Middle East, and well as parts of Africa and the Asia-Pacific. One of the deadliest conflicts in history,…