Any one of these:

The dilemma faced by President Woodrow Wilson when the U.S. Senate failed to ratify the League of Nations.
President Harry Truman’s decision to drop atomic bombs on Japan during World War II.
The moral dilemma that faced scientists who worked to create the atomic weapons developed during World War II.
President Johnson’s decision to escalate the war in Vietnam.

.The far reaching effects of the Watergate scandal and its cover-up!

.The Noble Experiment (Prohibition) and its effects on the country and the government!

.The Warren Commission; It’s report and how it affected the country and history!