Arab al-Ruha’, modern Urfa, in Turkey, the capital in antiquity of the Osrhoene peoples of northern Mesopotamia. Conquered by the Assyrians (8th century b.c.), it was called Ruhu (Syriac, Urhoi). Under Seleucus I (312–280 b.c.) its name was changed to Edessa and under Antiochus (175-162), to Antioch. In 132 b.c. it was the capital of the Kingdom of Edessa, or Osrhoene, under the Arab dynasty that was replaced by the Seleucids. Destroyed by the Romans under Trajan but rebuilt by Hadrian, it became a Roman military colony as Colonia Marcia Edessenorum in 217. Controlled by the Kingdom of Palmyra (c. 270), it fell to the Persians in 609 but was recaptured by the Byzantines under heraclius in 628, absorbed by the Arabs after 639, and retaken by Byzantium in 1031.
During the First Crusade, it was captured by Baldwin of Flanders (1098) but reverted to the Seljuk Turks in 1144. In 1182 the Sultan Saladin brought it under Egyptian control. It was destroyed by the Mongols (1391) and rebuilt by the Turks in 1637.
Edessa was evangelized by Christians from Palestine. Eusebius of Caesarea cites a legendary letter from the Chronicle of Addai, supposedly written by Abgar V Ukhama of Edessa to Christ, who sent the Apostle Addai to convert the country (Hist. Eccl. 1.13.1–22). The Epitaph of abercius contains the first certain evidence of Christianity. The Liber legum regionum (c. 250) narrates the conversion of King Abgar IX (179–216), a vassal of Osrhoene, but this evidence is questionable since Eusebius, who cites the text, omitted the conversion passage. However he quotes origen as saying that the Apostle Thomas preached to the Parthians in eastern Syria and in the 4th century the body of Thomas was venerated at Edessa (Hist. Eccl. 3.1.1). Eusebius likewise mentions the churches of Osrhoene as participating in the easter controversy (5.23.4) and the Chronicle of Edessa mentions the inundation of a church in 202. The first bishop, Palut, was consecrated by Serapion of Antioch (c. 200) and spread Christianity in East Syria and Persia. The peshitta and Tatian's Diatessaron apparently originated in Edessa, as did much of the Syrian apocryphal literature, such as the Acts of Thomas (3d century), the Psalms of Thomas (partly a Judeo-Christian composition of the 2d century), and apparently also the Odes of Solomon and the Gospel of the Truth. The primitive Christian monuments excavated at nearby dura-europos in Syria indicate that in this region appeared the first Christian buildings dedicated exclusively to religious service whose decorations were influenced by Judaic, Mithraic, and Greek art.
Edessan Christianity in the 3d century showed marks of stringent asceticism as instanced by the Acts of Thomas and the Tract on Virginity, as well as the vogue of spiritual marriage. tatian was there after 170, and also bardesanes (d. 222), the Gnostic hymn writer. It was affected by the persecutions of Decius and Diocletian.
The school of Edessa, rendered illustrious by ephrem the syrian (d. 373), was transferred to Nisibis in 457, and had considerable influence on the spread of Christianity in the Sassanid lands. Bishop rabbula of Edessa (412–435) was a strong anti-Nestorian, who requested that proclus of Constantinople write his Letter to the Armenians; however, Ibas of Edessa (435–457) was deposed as a Nestorian sympathizer at the Robber Synod of Ephesus (449), restored at the Council of chalcedon, but later condemned with the three chapters. The Nestorians were expelled in 457, and in the 6th century the Monophysites prevailed through the intrigues of James baradai (541–578).
With the Arab invasion Edessa lost significance but was the see of both a Nestorian bishop and a Jacobite metropolitan (until 1097) and produced the Jacobite James of Edessa (d. 708) and the Maronite Theophilus (d. 785). During the Crusades it likewise had a Latin metropolitan but in modern times has become a titular see. The Mission of the Capuchins opened in Edessa in 1841 was suppressed during World War I.
Bibliography: j. daniÉlou and h. marrou, Des Origines à saint Grégoire le Grand, v. 1 of Nouvelle histoire de l'Église (Paris 1963— ). j. tixeront, Les Origines de l'église d'Édesse (Paris 1888). a. von harnack, Die Mission und Ausbreitung des Christentums (4th ed. Leipzig 1924), Eng. The Mission and Expansion of Christianity, ed. and tr. j. moffatt (New York 1908). i. ortiz de urbina, "Le origini del cristianesimo in Edessa," Gregorianum 15 (1934) 82–91. h. leclercq, Dictionnaire d'archéologie chrétienne et de liturgie, ed. f. cabrol, h. leclerq and h. i. marrou (Paris 1907–53) 4.2:2058–2110. f. nau, Dictionnaire de théologie catholique, ed. a. vacant (Paris 1903–50) 4.2:2102–03. h. rahner, Lexikon für Theologie und Kirche, ed. j. hofer and k. rahner (Freiburg 1957–65) 3:658–659.