Pope Pius XI (31 May 1857 – 10 February 1939), born Ambrogio Damiano Achille Ratti, was Pope from 6 February 1922, and sovereign of Vatican City from its creation as an independent state on 11 February 1929 until his death on 10 February 1939. He issued numerous encyclicals including Quadragesimo Anno, highlighting capitalistic greed of international finance, and social justice issues, and Quas Primas, establishing the feast of Christ the King. He took as his papal motto, "Christ's peace in Christ's kingdom".
Achille Ratti was an accomplished scholar, librarian and priest. He celebrated his 60th birthday as a priest on 31 May 1917. Fewer than five years later, on 6 February 1922, he was elected Pope, succeeding Pope Benedict XV, who was only thirty months older and thus from the same generation as Ratti. In those five years, he had short stints as papal nuncio in Poland, in Kamionek, until being forced by the government to leave, and as Cardinal-Priest of Ss. Silvestro e Martino ai Monti and Archbishop of Milan, where he served only a few months before being elected Pope. He chose the name Pius, and his personality was strong, similar to Pius IX and Pius X. But as a scholar, he was open to science and research like no other Pope since Leo XIII.
To establish or maintain the position of the Church, he fostered and concluded a record number of concordats, including the Reichskonkordat with Germany. Under his pontificate, the longstanding hostility with the Italian government over the status of the papacy and the Church in Italy was successfully resolved in the Lateran Treaty of 1929. He was unable to stop the Terrible Triangle, consisting of massive Church persecution and killing of clergy in Mexico, Spain and the Soviet Union. While in Mexico and Spain the persecution was directed chiefly against the Catholic Church, hostility in the Soviet Union was directed against all Christians but especially against the Eastern Catholic Churches united with the Vatican. He vehemently protested against both Communism and Nazism as demeaning to human dignity and a violation of basic human rights, but heard so little support from the democracies of the West that he accused them of a Conspiracy of Silence. Against totalitarian demands, he fostered the freedom of families to determine on their own the direction of education of their children.
In one of his most important encyclicals on the social order of modern society, Quadragesimo Anno, he stated that social and economic issues are vital to the Church not from a technical point of view but in terms of moral and ethical issues involved. Ethical considerations include the nature of private property in terms of its functions for society and the development of the individual. He defined fair wages and branded the exploitation both materially and spiritually by international capitalism. He canonized important saints including Albertus Magnus, Thomas More, Petrus Canisius, Konrad von Parzham, Andrew Bobola and Don Bosco. He beatified and canonized Thérèse de Lisieux, for whom he held special reverence. He created the feast Christ the King in response to anti-clericalism. Pius XI took strong interests in fostering the participation of lay people throughout the Church, especially in the Catholic Action movement. The end of his pontificate was dominated by defending the Church from intrusions into Catholic life and education.