Pope Pius IX and Russia
The Pontificate of Pius IX began in 1847 with an agreement by which both the government and the Holy See played a part in filling vacant Latin Church episcopal sees in Russia proper and in its Polish provinces.
Pope Pius IX, who faced his own problems with revolutionary movements in his Church State, first tried to position himself in the middle, strongly opposing revolutionary and violent opposition against the Russian authorities, and appealing to them for more Church freedom.
Both the Holy See and the Russian government expressed their full satisfaction, which was not shared by the Russian Orthodox Church. The Accomodamento, while facilitating the establishment of new dioceses, did little to improve the situation of the Catholic Church at the local level.
In 1850, some 32 monasteries were closed and others limited in the recruitment of novices. Local priests were replaced with politically correct candidates, and vacant bishop sees were not allowed to be filled. A special problem continued to be the fate of the Oriental Churches, united with Rome, which were under pressure to unify with the Orthodox Church of Russia.
Tsar Alexander II claimed that only politically revolutionary elements were punished. On August 20, the Pope protested and ordered a prayer novena for the persecuted Church. But the persecutions worsened: 330 priests were deported, a war tax was imposed on the clergy, and 114 Catholic monasteries were closed.
International protest from Pope Pius enraged the Tsar and his regime, and led to an Austrian intervention, urging the Pope to be silent in the interest of the Polish Catholics. Russia answered with a break of the concordat on December 6, 1863. By 1870, not a single bishop from the Polish area under Russian control was left in his own diocese 
Diplomacy of Pope Leo XIII
Pope Leo XIII (1878–1903) attempted to improve the situation with diplomatic overtures, with little success. The nightmare of the Russian Church continued under him, more pleasant atmospherics not-withstanding. The 19th century dilemma, that impressive Papal condemnations may result in suffering, closure of episcopal sees, and decade-long interruption of religious services for, and education of the faithful, haunted Papal diplomacy in the 20th century, especially during the pontificates of Pope Pius XI, Pope Pius XII and Pope Paul VI.
- Acta Apostolicae Sedis ( AAS), Roma, Vaticano 1922-1960
- Acta et decreta Pii IX, Pontificis Maximi, VolI-VII, Romae 1854 ff
- Acta et decreta Leonis XIII, P.M. Vol I-XXII, Romae, 1881, ff
- Actae Sanctae Sedis, (ASS), Romae, Vaticano 1865
- L. Boudou, Le S. Siege et la Russie, Paris, 1890
- Owen Chadwick, The Christian Church in the Cold War, London 1993
- Handbuch der Kirchengeschichte, VII, Herder Freiburg, 1979, 355-380
- Matthias Erzberger, Erlebnisse im weltkrieg, Stuttgart,
- Herder Korrespondenz Orbis Catholicus, Freiburg, 1946–1961
- Andrey Micewski, Cardinal Wyszynski, A biography, Harcourt, New York, 1984
- Josef Schmidlin Papstgeschichte, Vol I-IV, Köstel-Pusztet München, 1922–1939
- John Gilmary Shea, The Life of Pope Pius IX, New York, 1877
- All sources if not otherwiese quoted, are Schmidlin, II, pp 213-224
- All sources if not otherwise quoted, are Schmidlin, II, pp 215-219
- All sources if not otherwise quoted, are Schmidlin, II, pp 219-224
- Andrey Micewski, Cardinal Wyszynski, A biography, Harcourt, New York, 1984, pp. 3
- Schmidlin, II, 506 ff
- Schmidlin, II, 508