What events led up to McCarthyism?

Answer 1

McCarthy himself had been accusing anyone he didn't like of being a Communist for all his adult life. But the events that put the wind into his sails were first, the virtual annexation of East European countries by the USSR after WW 2. Political leaders in the US had decided to keep it quiet that the USA and Britain had fully agreed with Stalin during the war at the Yalta Conference that he could bring these countries - most of them had sided with Nazi Germany against Russia during WW 2 - under Soviet control. But the general public in the West, not knowing of this agreement, saw it as proof of Soviet aggressiveness and expansionism.

The second factor was the atomic bomb. The Communists fully understood that this new weapon of the USA was putting them at a fatal disadvantage. Stalin therefore did everything in his power to catch up. And catching up also meant: getting hold of US documentation on the bomb through espionage. A number of Soviet spies - often bribed US citizens, including US civil servants - were caught. The news coverage of these events helped create the impression in the US that Soviet spies were all over the place.

McCarthy used the above events to create the idea that a huge Fifth Column of secret Communist sympathizers in the US was lying in wait to overthrow US institutions and values and replace them with Communism. Shamefully, only when he started to accuse high-ranking fellow politicians and Government members, US Congress finally stepped in to investigate the truth in McCarthy's accusations and found them 'a tissue of lies'.