Pope Leo XIII was the head of the Catholic Church from 20 February 1878 to his death in 1903. He was the oldest pope, with the exception of Pope Benedict XVI as emeritus pope, and had the third-longest confirmed pontificate, behind those of Pius IX and John Paul II.
He is well known for his intellectualism and his attempts to define the position of the Catholic Church with regard to modern thinking. In his famous 1891 encyclical Rerum novarum, Pope Leo outlined the rights of workers to a fair wage, safe working conditions, and the formation of trade unions, while affirming the rights of property and free enterprise, opposing both socialism and laissez-faire capitalism. He influenced Mariology of the Catholic Church and promoted both the rosary and the scapular.
Leo XIII issued a record of eleven papal encyclicals on the rosary, earning him the title as the "Rosary Pope". In addition, he approved two new Marian scapulars and was the first pope to fully embrace the concept of Mary as Mediatrix. He was the first pope to have never held any control over the Papal States, after they had been dissolved by 1870.