Why were many countries of Europe in danger of succumbing to communism following World War II?

After the fall of the Nazi Regime, the nations liberated by the USSR after the war had not been liberated at all but integrated as satellite countries (puppet-states) for the USSR called the Eastern Bloc. Communism was on the rise after the end of fascism and Stalin wanted to convert as many countries to communists as possible. The Warsaw Pact was also established to rival that of NATO and further integrate Eastern Europe into Communism. The Cold War had been a game of deception and bluffing so if the democratic side failed to keep up with Communists there would be Europeans leaning to be communist.

eastern europe, the region of europe that is east of germany, was heavily influenced by the byzantine empire. through byzantine traders, and more importantly, the church, byzantium influenced the art, literature, and architecture of the region

the speech revealed that eastern european countries were no threat to their neighbors, which led to the creation of the truman doctrine i think this might be correct.