World War I: The American entry into World War I begins when diplomatic relations with Germany are severed due to its unrestricted submarine warfare.

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. One of the deadliest conflicts in history, World War I resulted in an estimated 15 to 22 million deaths, including those in war crimes and genocides.…