The feast of this great Pope was transferred from the day of his death, November 10, 461, to April 11, the day on which his body was first laid in the tomb under the outer porch of the old St. Peter’s. He is called “Great,” not only for his learning, but also for his successful government of the Church by overcoming heretics and saving Rome form the invasion of Attila. The magnificent Offices of Advent are attributed to him and certainly several of his compositions are contained in the Leonine Sacramentary. By his humility, mildness, and charity this great Pope won the love and reverence of emperors, princes, and people of every rank.
(Source: Fr. Lasance, The New Roman Missal)