Prince (1187-1198) and king (1198-1219) of Armenia.
Leon succeeded his brother Prince Rupen III as leader of the Cilician Armenians, soon securing the country against Turcoman raids, and expanded his domain west, beyond Seleucia (mod. Silifke, Turkey), and north, beyond the Cilician Gates. His greatest achievement was the establishment of Cilicia as the center of a kingdom, a project that took several years. Leon first negotiated with the Holy Roman Emperor, Frederick I Barbarossa, for a royal crown, but these plans fell through when the emperor died while crossing Cilicia in 1190. During the efforts of the Third Crusade (1189-1192) to recover Outremer from Saladin, Leon sent troops to participate in the siege of Acre (mod. ‘Akko, Israel) and the conquest of Cyprus, pursuing friendship with the Franks despite border disputes with the principality of Antioch and the Templars. He was able to placate the pope without significantly changing Armenian ecclesiastical doctrine, and on 6 January 1198 he was crowned king in Tarsos (mod. Tarsus, Turkey) by the Armenian catholicos in the presence of the Syrian Orthodox patriarch, the local Greek Orthodox metropolitan, the papal legate, and the imperial chancellor; another crown was sent by the Byzantine emperor Alexios III Angelos.
King Leon arranged marriage alliances with Aimery of Lusignan, John of Brienne, and the princes of Antioch as well as with Theodore I Laskaris of Nicaea. He gave lands to the Teutonic Knights and the Hospitallers (the latter guarded his western frontier) and began the “Frankiciza- tion” of his court. Cilicia was increasingly important in trade between East and West, and Leon fostered this by granting privileges to Genoese and Venetian merchants. Much of his reign was taken up with the succession dispute in the principality of Antioch, where his great-nephew Raymond- Rupen was installed as prince in 1216 but ousted three years later. Leon died in 1219 and was succeeded by his daughter Isabel (Zabel).