French and Indian War - [1]

Korean War - "Some call it the forgotten war, but for two years America fought a full fledged war to keep South Korea free." History Central

Barbary Wars - largely passed out of popular memory within a generation.

World War I - "birthed World War II, along with the great totalitarian delusions communism, fascism and Nazism. Yet the Great War, as it was first called, is largely forgotten in America." [2]