Feast of the Holy Rosary
1 October, commemorating the remarkable response to the prayers of the rosary of the Blessed Virgin, notably the preservation of Europe from the Turks by the victory of Lepanto, 1511, after which Saint Pius V ordered a commemoration of the rosary on that day.
Gregory XIII allowed the observance of the feast of the Holy Rosary on the first Sunday in October in all churches having chapels or altars dedicated to the Blessed Virgin under that title.
Clement X granted it to all Spain, and Clement XI extended it to the universal Church after the victory of Prince Eugene over the Turks at Peterwardein, Hungary, in 1116.
Leo XIII inserted the invocation "Queen of the Most Holy Rosary" into the Litany of Loreto.
On this feast in every church which has a rosary confraternity, a plenary indulgence is granted on certain conditions to those who visit the rosary chapel or a statue of Our Lady.
New Catholic Dictionary