Leo XIII reversed much of the conservative political policy of Pius IX. He restored good relations with Germany; improved relations with Great Britain, Russia, and Japan; and established (1892) an apostolic delegation in Washington, D.C. His policy failed, however, in Italy. Italy refused to restore papal sovereignty over Rome, and Leo maintained the increasingly useless posture of "prisoner of the Vatican." He also failed to persuade French Roman Catholic leaders to support the Third Republic; his last years saw increasingly anti-Catholic French legislation.
The pontificate of Leo XIII was especially important for the leadership he gave on social questions. His most famous encyclical was Rerum Novarum on the condition of workers in the modern world. The document outlined the duties of both employers and workers, upholding the principles of collective bargaining, just wages, and private property. Leo also took an interest in education and opened the Vatican archives to all scholars. His pontificate was marked by an openness to scientific progress and concern for reconciling the church with the modern world.