What are a couple of example in American History when people shifted their ideologies from one set of beliefs to another and what were the political, economic, and social conditions that may have led up to these changes?

1. World War II caused the Republican Party to become more aware of international affairs, culminating in the election of General Dwight Eisenhower as president of the U.S.

2. As a result of the failure of the Democrat Party's leadership in the Vietnam War, the Democrat Party has become pacifist and withdrawn from a role of leadership in international affairs.

Two wars have effected a shift in ideology in American political parties.