How did Pius XII try to prevent war in Europe before World War II?

Pope Pius XII, elected in March 1939, sought to act as a "Pope of Peace" by utilizing his background as a diplomat to prevent the outbreak of World War II. His primary strategy involved maintaining the impartiality of the Holy See to serve as a mediator between European nations.1

To achieve this, he pursued a cautious diplomatic course, attempting to dissuade European governments from embarking on war through direct engagement and behind-the-scenes negotiations. His efforts included:

• Diplomatic Mediation: He attempted to keep Benito Mussolini from entering the war on the side of the Axis powers.1
• Avoiding Confrontation: He refrained from issuing an encyclical against Nazi Germany and fascist Italy, fearing that such a move would provoke reprisals and undermine his ability to act as a neutral arbiter.1
• Maintaining Impartiality: Even after the invasion of Poland, he insisted on remaining "above the fray" to preserve his position as a potential mediator, a stance that has been subject to significant historical debate regarding its effectiveness and moral implications.1