Summary:
- Pope Leo XIII was the Pope of the Catholic Church from 1878 to 1903, making him one of the longest-serving popes in history.
- During his 100-day papacy, Pope Leo XIII made many important decisions and changes, including issuing the encyclical "Rerum Novarum" which addressed the rights of workers and the relationship between the Church and the modern world.
- Pope Leo XIII was known for his progressive views and his efforts to modernize the Catholic Church, making him an influential figure in the history of the Church and in the world.