Feast of the Immaculate Heart of Mary.
IMMACULATE HEART OF MARY - Saturday after the Feast of the Sacred Heart of Jesus
The feast springs from contemporary piety but has its roots in the Marian apostolate of St. John Eudes (1680), and outstanding apostle of devotion to the the Hearts of Jesus and Mary. After repeated requests and repeated refusals between 1669 and 1729, on December 8, 1942, the twenty-fifth anniversary of the apparitions at Fatima, Pope Pius XII dedicated the Church and the human race to the Immaculate Heart of Mary. He placed the feast on August 22 and extended it to the entire Latin Church. It has now been moved closer to the feast of the Sacred Heart of Jesus always falling on the Saturday after the Feast of the Sacred Heart of Jesus.
www.thesacredheart.com/feastmar.htm