Final answer:
The Palmer Raids were closely related to the fear of communism and radicalism. Thousands were arrested and deported under suspicion of being radicals, but public support for the raids waned when predicted uprisings did not occur.
Step-by-step explanation:
The Palmer Raids of 1919 to 1920 were most closely related to the fear of communism and radicalism. These raids were a reaction to the growing fear of a communist threat, including the belief that immigrants might bring radical ideologies. The Attorney General A. Mitchell Palmer, with the support of J. Edgar Hoover, carried out controversial surveillance tactics and without proper search warrants targeted suspected labor organizers, leftists, and political dissidents. The mass arrests and deportations of these raids were a clear demonstration of the government's preparedness to ignore individual rights and civil liberties in the face of perceived national threats.
In addition to hunting down socialists and communists, these raids were intertwined with the broader fear of anarchists. The raids resulted in thousands of arrests and the deportation of many foreign-born radicals, often without evidence or trials. Public opinion eventually turned against Palmer when his predictions of a revolutionary plot did not come to fruition, leading to skepticism about the actual extent of the radical threat and the legitimacy of his actions.