Who was Joseph McCarthy and how did he affect US history?

Joseph McCarthy was a US senator in the 1950's who lead a paranoid campaign against communist subversion, which involved many false accusations and unjust persecutions, and which is generally described therefore as a witch hunt; it was a disgraceful episode of American history. As is often the case with paranoiacs driven by hatred, McCarthy ultimately destroyed himself. He was censured by the rest of the Senate, and died in a hospital for alcoholics less than two years after leaving office.