The United States had ended the war with a homefront almost completely intact, with what could be considered a modest loss of 740,000 personel killed in action. Nonetheless the nation was still traumatized, both firsthand as millions of young men returned with both mental and physical scars, and ideologically. America had in the eyes of many led the world to victory over both of the new opponants to democracy, but what they'd seen scared them. "Communist" practically became the new C-word in many postwar American families, something to be feared, hated, but never spoken of.
The Political Subversion Act of 1945 remained in effect after the war, and its perhaps purposely vague definition of an enemy of the nation meant that it was applied liberally. In a rather brutal twist of fate, many of the first to be arrested were returning soldiers, some of whom were even arrested as they stepped off their ships. After the act had been passed in July, officers had been instructed to report any suspicions of Communist or Fascist ideology, and the FBI spent more money investigating potential domestic communists than pursuing actual spies. By wars end over two million Americans were on various lists that put them in the spotlight, but very few of these were current or even repentant Communists. Given that these people were small enough in number that the FBI exhausted them quickly, they moved down the list.
First were the Socialists, party members and those who were self described. Some men who'd voted Socialist once as far back as 1916, before the Soviet Union was even founded. After that any remaining Facists, and various smaller 'problematic' political parties were swept up. Before long the targets of the bill seemed picked less for their threat to America, and more for their threat to the interests of various people in high places. Union leaders in particular were targeted, almost 20% of them were arrested by 1947, many more chose to disband. Civil rights groups were also hit hard, many of those arrested were simply done to obstruct their efforts to organize.
It should be noted that just because these people were arrested (812,000 in total) doesn't mean they were convicted, in fact less the 5% of them were. But even being arrested, held without bail in many cases, and waiting in clogged federal jails, was traumatizing and disruptive. Local papers often advertised who'd been arrested each morning, and many completely innocent people were tormented by those who saw themselves as more loyal. Many who spoke out against all this were placed under investigation, which in itself was a terrifying period of waiting to see if they'd be arrested. Such arrests were usually at night with no warning, several dozen were killed in shootouts with the police. In one case a young married immigrant couple in Boston was arrested, and despite their pleas no effort was made to care for their infant son, who starved to death in his crib long before either of them were released.
The fact that merely a baseless accusation could place you under ingestigation led to widespread paranoia, which tore families apart. One man in Nevada even murdered his sister due to her past Communist party membership, though thankfully he was still convicted. With fear and political terror gripping the nation most wanted change, but few were willing to speak out. Ironically it would be the military that would protect the people from their own state. The highest ranking and well known generals of the war were largely spared from any scrutiny, though their families weren't always as forturnate.
Perhaps the final straw occured in April of 1946, when J Robert Oppenheimer's Wife, Brother, and sister in-law were arrested under the act. General Eisenhower, despite his new position as chief of staff of the army and despite President Morganthau's insistance otherwise, defended the Oppenheimers in a fierce series of letters to the press. Several generals, notably including Patton, rallied behind their old commander. Patton even famously said in one interview "Why arrest him? Do you know how many fucking Russian widowers there are because of that great man? I'd let him punch me for all I care."
In the end the whole affair proved the first nail in the coffin for the act, it was clear the public wouldn't tolerate this proscription. The act was reviewd by the supreme court once again that summer, and finally abolished after a few hasty revisions in January 1947. It was far too late to save Morganthau though, polling that year showed that his approval were ratings at perhaps as low as 15%. Morganthau chose not to stand for reelection, and instead the democrats sought to salvage their reputation by asking Eisenhower to run. He reluctantly agreed, and in 1948 won the largest landslide in electoral history, carrying every state against the republican sacrificial lamb Hugh Butler. Eishenhower was describe as a long overdue stiff drink for the nation, and promised never to throw the nation into fear and terror again, a promise he delivered.