Assuming you're referring to World War I, the main event that moved the United States from neutrality to war was the sinking of the Lusitania, since many Americans died, and it was the Germans who were responsible.
The USS Maddox incident, drew the U.S. more directly into the Vietnam War. Which involved <span>two separate confrontations involving North Vietnam and the United States in the waters of the Gulf of Tonkin.</span>
<span>wiped almost 66% of Europe, </span>
The term that is defined as “a legal doctrine that permitted racial segregation in public facilities" would be "Jim Crow", which was a series of such laws passed in the South after the Civil War.