Most people in 1861 expected the North to easily defeat the South and quickly win the war. Why did the war last for four years, proving this assumption false?

People in the North and the South had been struggling against each other for so long ... parties, and patriotic speeches made it easy for both sides to recruit soldiers. ... Most people did not expect the war to last very long, so some ... men had joined the Union Army, most of them for two- or three-year terms.

Explanation:

answer; /// i believe that the correct answer is (d)the huang he river valley;

it broke up the ottoman empire (just a small fact) and the turkish leaders lost many soldiers.