Identify the underlying and immediate causes of World War I and explain why the United States moved from neutrality to entering the war in 1917.
World War I began in Europe in 1914 from a combination of long-building pressures historians often summarize with the acronym MAIN: Militarism (an arms race and glorification of military strength), Alliances (a tangle of defense treaties that meant one small conflict could drag in many nations), Imperialism (competition for colonies bred rivalry among European powers), and Nationalism (intense pride and rivalry between ethnic and national groups, especially in the unstable Balkans). The immediate spark came on June 28, 1914, when a Bosnian Serb nationalist assassinated Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, in Sarajevo. Alliance obligations then pulled in one power after another within weeks: Austria-Hungary against Serbia, Germany backing Austria-Hungary, Russia backing Serbia, France and Britain joining Russia against Germany. What might have stayed a regional crisis became a war stretching from Belgium to the Middle East.
President Wilson initially declared American neutrality "in thought as well as in deed," and most Americans supported staying out of what looked like a European quarrel. Neutrality eroded for specific, traceable reasons. Germany's use of unrestricted submarine warfare sank the British liner Lusitania in May 1915, killing 128 Americans among nearly 1,200 total dead, and while Germany temporarily scaled back submarine attacks after American protests, it resumed unrestricted submarine warfare in early 1917, gambling it could defeat Britain before America could mobilize. Then British intelligence intercepted the Zimmermann Telegram, in which Germany secretly proposed that Mexico attack the United States in exchange for help reclaiming Texas, New Mexico, and Arizona if the U.S. entered the war. Between resumed submarine attacks and the Zimmermann Telegram's public release, Wilson asked Congress for a declaration of war on April 2, 1917, arguing the world "must be made safe for democracy." Congress agreed four days later.
Mastery looks like: They can state all four MAIN causes, explain the assassination's role as the immediate spark, and sequence at least two specific events that moved the U.S. from neutrality to war.
Common stumbles: Treating the assassination of Franz Ferdinand as the sole cause of the war, rather than as the spark that ignited already-flammable underlying conditions.