In late 1946, Martinů finally received the official offer to teach in Prague, now coming from the newly established Musical Academy of Performing Arts. Yet his precarious state of health prohibited him from making any commitment through the next year. In February 1948, the communist coup put to an end any plans to work at home. Thus, in June 1948, he accepted an offer to teach at Princeton University, which—along with his position at the Mannes Music School—offered him financial security for the time being.

These changes in fortunes made any offers from Prague—past, present, or future—unworthy of consideration. Now, in the “new Czechoslovakia,” under the direction of a number of zealous and opportunistic young musicians, the Sovietization of music began in earnest. Directing the purge of noncommunists from musical institutions was Miroslav Barvík (1919–98), who—as counterpart to Tikhon Khrennikov in the Soviet Union—would come to the helm of musical life as Secretary General of the Union of Czechoslovak Composers (see fig. 18). Barvík also served as Editor in Chief of the Party music journal Hudebni rozhledy, which— with all other music journals discontinued—would help to show the path for creating the new socialist repertoire. Becoming the Dean of Prague's Musical Academy of Performing Arts was Antonín Sychra (1918–69), who released what is perhaps the most notorious guidebook for composing socialist music under the title Party Music Criticism. Finally, becoming the new director of cultural programming at Czechoslovak Radio was Jaroslav Jiranek (1922–2001), who became the most eminent musicologist of the communist period and remained active as a party ideologue until the fall of communism and even beyond.

These figures were all part of a third generation of the Nejedlý School, which would now mesh Nejedlý's ideas with Soviet socialist realism. Part of the new politicization of music meant calculating measures against perceived opponents according to the needs of a country that had become part of the Soviet Bloc. Martinů, by this point, was seemingly a permanent resident of the United States, considered the leader of the “bourgeois West,” thus his censure came as a matter of course.