Following the death of Pope Pius XII, the conclave met to elect a new pope, facing pressure for progressive changes within the Catholic Church. The election took place in the Sistine Chapel, under the intense scrutiny of the global community. Cardinal Angelo Giuseppe Roncalli, previously the Patriarch of Venice, was chosen as the new pontiff, taking the name John XXIII. His selection was surprising to many, as he was not considered a frontrunner. Upon his election, he quickly gained the affection of the Church and the public for his approachable demeanor and pastoral focus.

John XXIII was noted for his efforts to foster openness and dialogue within the Church and the wider world. At the age of 76, he was an experienced diplomat, which played a role in his electability amongst the cardinals seeking a leader able to navigate the Church's challenges during the Cold War. His papacy was characterized by calls for reform, leading to the Second Vatican Council, which aimed to address modern issues and engage with contemporary society. He emphasized peace and unity at a time when the global landscape was fraught with tension.

Pope John XXIII's papacy introduced significant changes in church practices and attitudes, including liturgical reforms and a renewed emphasis on ecumenism. These changes were instrumental in modernizing the Church's relationship with the world, providing a more relevant approach to spirituality in the post-war era. His legacy continues to influence the Catholic Church's mission and operations today.