Pope Pius XII, born Eugenio Pacelli in 1876, served as the head of the Roman Catholic Church from 1939 until his death in 1958. He is known for his leadership during World War II and his efforts to address the challenges faced by the Church during a time of global conflict. His papacy was marked by a focus on diplomacy and maintaining neutrality in the war. Pope Pius XII was also involved in various social issues, including the promotion of peace and humanitarian efforts. His encyclicals, such as Mystici Corporis Christi, emphasized the importance of the Church's role in the modern world. His legacy remains a topic of debate among historians and theologians.