From a series of letters by Archbishop Theophylact of Ohrid, it appears that Gregory Taronites originally held some civilian office in the Balkans, before being entrusted with a mission to the Pontus ca. 1101–1103. There, according to Theophylact, he triumphed against the Seljuk Turks and the Franks, the latter probably a reference to his role in ransoming Bohemond I of Antioch, who had been a captive of the Turks at Neokaisareia since his defeat in the Battle of Melitene in 1100. After completing his mission with success, Gregory returned to Constantinople, where Alexios I named him "doux" (military governor) of the theme of Chaldia in the Pontus.