III. The military governors (, strategoi) were powerful figures, whose access to the resources of their extensive provinces often provided the means of rebellion. The Opsikion theme had been the power-base that enabled the rebellion of Artabasdos, and was also the theme situated nearest to the capital within Asia Minor. Constantine reduced the size of this theme, dividing from it the Bucellarian and, perhaps, the Optimaton themes. In those provinces closest to the seat of government this measure increased the number of strategoi and diminished the resources available to any single one, making rebellion less easy to accomplish. Constantine was responsible for the creation of a small central army of fully professional soldiers, the imperial tagmata (literally: 'the regiments'). He achieved this by training for serious warfare a corps of largely ceremonial guards units that were attached to the imperial palace, and expanding their numbers. This force was designed to form the core of field armies and was composed of better-drilled, better-paid, and better-equipped soldiers than were found in the provincial themata units, whose troops were part-time soldier-farmers. Before their expansion, the vestigial Scholae and the other guards units presumably contained few useful soldiers, therefore Constantine must have incorporated former thematic soldiers into his new formation. Being largely based at or near the capital, the tagmata were under the immediate control of the Emperor and were free of the regional loyalties that had been behind so many military rebellions. The fiscal administration of Constantine was highly competent. This drew from his enemies accusations of being a merciless and rapacious extractor of taxes and an oppressor of the rural population. However, the empire was prosperous and Constantine left a very well-stocked treasury for his successor. The area of cultivated land within the Empire was extended and food became cheaper; between 718 and c. 800 the corn (wheat) production of Thrace trebled. Constantine's court was opulent, with splendid buildings, and he consciously promoted the patronage of secular art to replace the religious art that he removed. Constantine constructed a number of notable buildings in the Great Palace of Constantinople, including the Church of the Virgin of the Pharos and the porphyra. The porphyra was a chamber lined with porphyry, a stone of imperial purple colour. In it expectant empresses underwent the final stages of labour and it was the birthplace of the children of reigning emperors. Constantine's son Leo was the first