| Succession: | Roman emperor |
| Moretext: | in the East |
| Reign: | 7 February 457 – |
| Coronation: | 7 February 457 |
| Cor-Type: | Coronation |
| Predecessor: | Marcian |
| Successor: | Leo II |
| Reg-Type: | Western emperors |
| Birth Date: | 401 |
| Birth Place: | Dacia Aureliana, Roman Empire |
| Death Date: | 18 January 474 (aged 73)[1] |
| Death Place: | Constantinople, Eastern Roman Empire |
| Spouse: | Verina |
| Issue: | Ariadne, Leontia, unnamed son |
| Regnal Name: | Latin: [[Imperator]] [[Caesar (title)|Caesar]] [[Flavia (gens)|Flavius]] Leo [[Augustus (title)|Augustus]] Greek, Ancient (to 1453);: [[Autokrator|Αὐτοκράτωρ]] καῖσαρ Φλάβιος Λέων αὐγουστος |
| Dynasty: | Leonid |
| Religion: | Chalcedonian Christianity |
| Honorific Prefix: | Saint |
| Leo the Great | |
| Feast Day: | 20 January |
| Venerated In: | Eastern Orthodoxy |
| Titles: | Holy and Right-Believing Emperor of the Romans |
| Attributes: | Imperial attire |
Leo I (; 401 – 18 January 474), also known as "the Thracian" (Latin: Thrax; Greek, Ancient (to 1453);: ο Θραξ), was Roman emperor of the East from 457 to 474. He was a native of Dacia Aureliana near historic Thrace. He is sometimes surnamed with the epithet "the Great" (Latin: Magnus;), probably to distinguish him from his young grandson and co-augustus Leo II .
Leo proved to be a capable emperor who ruled the East for nearly 18 years. He oversaw many ambitious political and military plans, aimed mostly at aiding the faltering Western Roman Empire and recovering its former territories. He is notable for being the first Eastern Emperor to legislate in Koine Greek rather than Late Latin.[2] He is commemorated as a saint in the Eastern Orthodox Church, with his feast day on 20 January.[3] [4]
He was born in Thracia or in Dacia Aureliana province in the year 401 to a Thraco-Roman family. His Dacian origin is mentioned by Candidus Isaurus,[5] while John Malalas believes that he was of Bessian stock.[6] He served in the Roman army, rising to the rank of comes rei militaris. Leo was the last of a series of emperors placed on the throne by Aspar, the Alan serving as commander-in-chief of the army, who thought Leo would be an easy puppet ruler. Instead, Leo became more and more independent from Aspar, causing tension that would culminate in Aspar's assassination.
Leo's coronation as emperor on 7 February 457, was the first to add a Christian element to the traditional Roman procedure, having been performed by the Patriarch of Constantinople,[7] a fact which symbolized the transformation of Roman imperial traditions into Medieval Roman and Christian ones. This Christian coronation ritual was later imitated by courts all over Europe,[8] especially in the West in the course of Late Antiquity.
Leo I made an alliance with the Isaurians and was thus able to eliminate Aspar. The price of the alliance was the marriage of Leo's daughter to Tarasicodissa, leader of the Isaurians, who, as Zeno, became emperor in 474. In 469, Aspar attempted to assassinate Zeno[9] and very nearly succeeded. Finally, in 471, Aspar's son Ardabur was implicated in a plot against Leo but was killed by palace eunuchs acting on Leo's orders.[10]
Leo sometimes overestimated his abilities and made mistakes that threatened the internal order of the Empire. The Balkans were ravaged by the Ostrogoths, after a disagreement between the Emperor and the young chief Theodoric the Great, who had been raised at Leo's court in Constantinople, where he was steeped in Roman government and military tactics. There were also some raids by the Huns. However, these attackers were unable to take Constantinople thanks to the walls, which had been rebuilt and reinforced in the reign of Theodosius II and against which they possessed no suitable siege engines.
See main article: Vandal War (461-468). Leo's reign was also noteworthy for his influence in the Western Roman Empire, marked by his appointment of Anthemius as Western Roman emperor in 467. He attempted to build on this political achievement with an expedition against the Vandals in 468. 1,113 ships carrying 100,000 men participated in the expedition, which ended in defeat because of bad leadership from Leo's brother-in-law Basiliscus. This disaster drained the Empire of men and money. Procopius estimated the costs of the expedition to be 130,000 pounds of gold; John the Lydian estimated the costs to be 65,000 pounds of gold and 750,000 pounds of silver.
Leo died of dysentery at the age of 73 on 18 January 474.[11] [12] [13]
Leo and Verina had three children. Their eldest daughter Ariadne was born prior to the death of Marcian (reigned 450 – 457).[14] Ariadne had a younger sister, Leontia. Leontia was first betrothed to Patricius, a son of Aspar, but their engagement was probably annulled when Aspar and another of his sons, Ardabur, were assassinated in 471. Leontia then married Marcian, a son of Emperor Anthemius and Marcia Euphemia. The couple led a failed revolt against Zeno in 478–479. They were exiled to Isauria following their defeat.[15]
An unknown son was born in 463. He died five months following his birth. The only sources about him are a horoscope by Rhetorius and a hagiography of Daniel the Stylite.
[15] The Georgian Chronicle, a 13th-century compilation drawing from earlier sources, reports a marriage of Vakhtang I of Iberia to Princess Helena of Byzantium, identifying her as a daughter of the predecessor of Zeno.[16] This predecessor was probably Leo I, the tale attributing a third daughter to Leo. Cyril Toumanoff identified two children of this marriage: Mithridates of Iberia; and Leo of Iberia. This younger Leo was father of Guaram I of Iberia. The accuracy of the descent is unknown.