Summi Pontificatus

Summi Pontificatus is an encyclical of Pope Pius XII published on October 20, 1939. The encyclical is subtitled "On the Unity of Human Society." It was the first major encyclical of Pius XII so was seen as setting "a tone" for his papacy. It critiques major errors at the time, such as ideologies of racism and cultural superiority and the totalitarian state. It also sets the theological framework for future encyclical letters, such as Mystici Corporis Christi (1943). The encyclical laments the destruction of Poland, denounces the Molotov-Ribbentrop Pact, and calls for a restoration of independent Poland.

Read more about Summi Pontificatus:  The Unity of Human Society, The Totalitarian State, Consequences, Source