Answer:
Plessy v. Ferguson was a landmark 1896 U.S. Supreme Court decision that upheld the constitutionality of racial segregation under the “separate but equal” doctrine. The case stemmed from an 1892 incident in which African American train passenger Homer Plessy refused to sit in a car for blacks. Rejecting Plessy’s argument that his constitutional rights were violated, the Supreme Court ruled that a law that “implies merely a legal distinction” between whites and blacks was not unconstitutional. As a result, restrictive Jim Crow legislation and separate public accommodations based on race became commonplace.
The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary. In June 1914, a Serbian-nationalist terrorist group called the Black Hand sent groups to assassinate the Archduke. Hope this helps, plus this was the main reason why it happened plus if you see a link other people offer for the answer don’t put it in the web, I tested it out I got a virus. Anyways hope this helps!
