<span>The Adams–Onís Treaty of 1819, also known as the Transcontinental Treaty, the Florida Purchase Treaty, or theFlorida Treaty, was a treaty between the United States and Spainin 1819 that ceded Florida to the U.S. and defined the boundary between the U.S. and New Spain.</span>
There are different parties so people feel different
D) To fight the spread of communism.
Because of the Domino Theory they thought that if Vietnam fell into Communism, the whole region would follow. So therefore they wanted to support South Vietnam in order to contain Communism in Asia.
It was feudalism. you have to look at the frame of the crusades.