Not for nothing did World War I feature the song "How you gonna keep 'em down on the farm once they've seen Paree". Harry Truman once considered joining the KKK as a political move in the 1930s...but didn't, because of their hate of Catholics, whom Truman had served with in WWI and had come to view differently from direct experience.
Women gained new confidence and foot-holds from their independence gained during WWII, where they served in theaters of war AND took on many male-dominated roles at home. Roles many women were loathe to give up when the war finished.
The Korean War led to Truman completely desegregating the armed forces. Hell, Sidney Poitier's movie "All the Young Men..." was about this very topic. By Vietnam, things changed dramatically.
Wars don't end racism or intolerance or any such thing...but they DO have an influence. I don't think it's a coincidence that the Civil rights movement got a huge boost following World War II (remembering that landmark cases like Brown v. Board of Education happened in 1950 and 1951). But expecting people to suddenly and utopically change isn't realistic. Lasting change comes slowly. But take heart that it DOES come.