12 Leo then urged Theodosius and Pulcheria in many letters to wipe out this stain. He proposed that they should remedy this sad state of affairs by summoning a council in Italy to reverse the decrees made at Ephesus. When the Emperor Valentine III, his mother Galla and his wife Eudoxia were entering St. Peter's Basilica, he received them accompanied by an assembly of bishops, and besought them with sighs and tears to do all they could to remedy the evil condition of the Church. The emperor wrote to his brother emperor [in the East], and the royal ladies joined their entreaties to his. But it was all to no purpose. Theodosius was in the hands of evil counselors and did nothing to amend the evil. However, he died suddenly; his sister Pulcheria succeeded him and took as her consort on the throne and in marriage one Marcian. Both of these persons were distinguished by their renown for wisdom and true religion. Then Anatolius, who had been illegally raised by Dioscorus to the see of Constantinople, accepted the letter which St. Leo wrote to Flavian on the Incarnation of our Lord. The remains of Flavian were brought back to Constantinople with great solemnity. The exiled bishops were restored to their sees, and the general hostility to the heresy of Eutyches grew so strong that there scarcely seemed to be any further need for a council. To this result the invasions of the barbarians, which were jeopardizing the safety of the Roman empire, also contributed.
Source: Sempiternus Rex Christus (Vatican.va)