Saint Dalmatius was archmandrite of the Dalmatian Monastery of Constantinople and for a time held the title Archmandrite of the Monasteries
Before becoming a monk, Saint Dalmatius was married with a family and served in the second company of Guards under Theodosius the Great. He received a call to enter into Monastic life and was taught by Saint Isaac of Dalmatia. Saint Dalmatius played a critical role during the Nestorian heresy. Following Saint Cyril of Alexandria's instructions, Saint Dalmatius left the monastery for the first time in 48 years with an army of monks behind to martch to the palace of Theodosius II. When they arrived, Theodosius was so stunned to see Saint Dalmatius outside his monastery in so long that he granted the request and heard Saint Cyril's case which ultimately led to his vindication and the downfall of Nestorius.
Saint Dalmatius's feast day is celebrated on August 3rd.