“If we but knew where we stand and whither we are tending,” declared the CP's new general secretary, Eugene Dennis, in February 1946 – in a phrase borrowed from an address by Abraham Lincoln – “we should then know what to do and how to do it.” Dennis and his comrades, he insisted, knew where they stood and whither history was tending, what was to be done, and how. But as it turned out, they were wrong on all counts. To understand how it happened, we have to return now to the immediate postwar years and follow them through to the mid-1950s.

From roughly 1947 through 1953, the CP was torn internally by its own hunts for heresy (“right-wing opportunism,” “ultraleftism,” “Trotskyism,” “Titoism,” and, especially, “a whole series of manifestations of white chauvinism within various Party organizations and even within the ranks of leading committees of the Party”). The Communists held their own political “trials” and purged longtime comrades who now were deemed “unreliable elements” and, at the least, excoriated others – among them, leading CIO unionists – for engaging in one or another alleged “wrongful tendency” or “objective deviation.”

Gripped by an apocalyptic mood heightened by the passage of the Internal Security Act (McCarran Act) in late 1950 and then by the Supreme Court decision, on June 4, 1951, upholding the Smith Act convictions and sentences of eleven top party officials – which, said Dennis, was “the five minutes to midnight” bell – the party's leaders made the fateful decision to go “underground.”