Pope Leo XIII publishes Supremi apostolatus officio on the Rosary

Background. Pope Leo XIII, born Gioacchino Vincenzo Raffaele Luigi Pecci, served as head of the Catholic Church from 1878 until his death in 1903. During his papacy, he wrote a total of 86 encyclicals. Supremi apostolatus officio was the first of a number of these encyclicals specifically addressing the Rosary, marking the beginning of his extensive writings on this devotion.

Promulgation. The encyclical Supremi apostolatus officio, liturgically titled "The Supreme Apostolic Office," was issued on 1 September 1883. It is commonly referred to as "On Devotion of the Rosary." The document explicitly encouraged the practice of the Rosary, establishing a foundation for subsequent papal teachings on the subject during Leo XIII's pontificate.

Historical Context. The encyclical was issued on 1 September 1883, early in Leo XIII's pontificate, which had begun in 1878. It is commonly referred to as "On Devotion of the Rosary" and is the first of a number of encyclicals on that devotion. The legacy location 'Vatican City, Vatican' is anachronistic, as Vatican City did not exist until 1929; the supplied passages do not state a place of issuance, so the location is recorded as unresolved.