Final answer:
Joseph McCarthy's strategy was initially successful due to targeting individuals easily accused, having strong political allies, and public support for anti-Communist measures, but his unsubstantiated claims and aggressive tactics led to his downfall, ending with the Army-McCarthy Hearings and Senate censure in 1954.
Step-by-step explanation:
Joseph McCarthy's strategy can be considered the main reason for his initial success due to several key factors. Firstly, McCarthy targeted individuals who were easy to accuse without necessitating substantial evidence, which allowed him to create an atmosphere of fear wherein few would challenge him. Secondly, he had a number of strong political allies, such as prominent Republican Senator Robert Taft and Congressman Richard Nixon, who supported him because they saw an advantage in doing so for their party's anti-Communist stance.
However, McCarthy's lack of substantiation for his claims and his often unsubstantiated and sweeping accusations—referred to as McCarthyism—eventually led to his downfall. This culminated in the nationally televised Army-McCarthy Hearings in 1954, where his approach to accusations was publicly rejected, and he was subsequently censured by the Senate.