What three events led Americas fear of communism?

Answer 1

Focussing on the post-WW 2 era, there were three main events. The first was the Communist takeover of seven eastern European countries immediately after the war. Britain and the USA kept quiet about the fact that they themselves had during the Yalta conference agreed to this takeover . In consequence, the general public in the West saw the takeover as 'naked Communist aggression'.

The second event was the development of the US atomic bomb. The Soviet Union quickly realized that this put them at an enormous strategic an military disadvantage, and they frantically scrambled to get an atomic bomb of their own. This meant among other things, getting hold of documentation that could only be found in the USA. The Soviet Union therefore engaged and bribed US civil servants to get them copies of that documentation. Ultimately they were succesful, but in several cases the US spies were caught, leading to much-pubicized court cases and a general feeling that Communist spies were 'everywhere'.

Finally, there was US Senator McCarthy, who had a long history (even long before WW 2) of seeing Communist spies under every bed and accusing every political adversary of being a Communist sympathizer. The Communist takeover of several European countries and the trials of several Communist spies in the USA finally gave credence to his 'Red scare' rantings, and his blend of intimidation and blackmail of suspects led to a wave of accusations and convictions of supposed Communists. When McCarthy went over the top and started accusing his fellow-Congressmen of being Communists, the end quickly came for him. Congress finally started an investigation of these and earlier accusations and found them to be 'a tissue of fabrications'. Nevertheless, the lives and careers of many of the people that McCarthy had accused never recovered.