How did the Cold War further the career of Senator Joseph McCarthy? How did his career end?
The rise of Communism gave him his power but in the end, his vitriol was his ruin.
As soon as World War 2 ended, the Soviet Union took possession of all territory it held at the end of the war. This meant every country on Russia's border became a satellite country for Moscow.
Then in 1949 the communist party in China came into power with the overthrow of the democratic government. This was the beginning of what was called "the red scare."
Also, Russia entered into the "arms race" which was the building of nuclear weapons. The US was shocked when Russia set off its first hydrogen bomb. From there Russia built bigger and bigger nuclear bombs.
During those years there was the a general knowledge that some Americans joined the communist party. McCarthy took that to mean they were in favor of overthrowing the government, that they were getting orders from Moscow to engage in subversive activities.
McCarthy assembled a "Committee on un-American Activities" which investigated anyone with known communist leanings and anyone they thought had such leanings.
McCarthy played upon the fears of the American public. He increased his power by using fear against the public at large. To defend anyone who stood accused was to be a sympathizer yourself and put your own freedom in jeopardy.
The end came when McCarthy charged that the army was soft on communism. The army sent a lawyer to the hearings, a soft-spoken man named Joseph N. Welch. He challenged McCarthy by saying, "Until this moment, Senator, I think I never really gauged your cruelty or your recklessness.” It was then McCarthy’s turn to be stunned into silence, as Welch asked, “Have you no sense of decency, sir, at long last?”
Welch's challenge spelled the end of McCarthy. His committee was disbanded and McCarthy lost his re-election in 1956.