Truman was the one who adopted a policy of containment. This (arguably) aggressive approach was what influenced America to get into wars such as the Korean War and other smaller conflicts. Meanwhile, Eisenhower was a bit less aggressive. Although his Secretary of State Dulles preached Brinksmanship and was very anti-Soviet, Eisenhower himself was somewhat against this, as shown when he did nothing to prevent the Hungarian Revolt. He also sought to increase U.S-Soviet Relations in the Spirit of Geneva, but the U-2 Incident pretty much erased most of his progress.
C i believe i might be wrong
Lots of civil wars and the invasions of barbarians like the huns and other tribes brought down the empire since the senator could not get along and refused to fix the problem.