The Vatican was one of the seminal Cold Warriors, rejecting communism as early as the 1840s. It had hoped for the “containment” of Soviet-style expansionism into Europe during World War II, i.e. even before the United States adopted that term into its official Cold War vocabulary in 1946-47. However, the Vatican realized by the late 1950s that ideological rigidity damaged its own interest—ensuring the continued existence of functional churches behind the Iron Curtain. Mainly for this reason, it decided to engage with the communist world in the 1960s, although its policies were fraught with political danger and disappointments. Its major success in the European Cold War—the restoration of the Polish Church to independence—only occurred in the context of détente in German-German and European affairs in the early 1970s.