Constantine V was one of the most talented men to sit the Byzantine throne. He was also one of the most reviled by later historians because of his Iconoclasm. Upon becoming emperor in 741, Constantine was briefly ousted from power, and from Constantinople, by his brother-in-law Artabasdos. By November Constantine had regained control and kept it. Artabasdos and his sons were blinded. Constantine successfully campaigned in the East where the Umayyad caliphate was in its death throws, and in the Balkans he crushed the Bulgars in 763. Constantine reformed the army, creating a mobile force based in Constantinople, the tagmata. One failure was in Italy where Constantine did not even attempt to prevent the fall of the Byzantine capital, Ravenna, to the Lombards in 751.
Constantine was a more vigorous Iconoclast than his father had been. During his reign Iconophiles in the army and administration, in the Church, and in monasteries were persecuted and an Iconoclast theory of images was developed, enshrined in the acts of the Council of Hiera in 754. Constantine's Iconoclasm led to a breach with the papacy and it is perhaps in this context that we should see the emperor's transfer of ecclesiastical jurisdiction over Sicily, south Italy, and the Balkans from Rome to Constantinople. In spite of the negative image passed down to us by later sources when Constantine died in 775, he was popular with the army and the people of Constantinople. He repopulated the capital following an outbreak of the plague, repaired the Aqueduct of Valens, restoring the supply of clean, fresh water to the city, and also supplied plentiful and inexpensive food.
Constantine’s seals are aniconic, and differ from Leo III’s later seals only in the order of the imperial names. Indeed, one can follow the Isaurian dynasty on seals and silver coins by watching the names Leo and Constantine reverse themselves. The innovations seen in the gold coinage, where portraits of deceased emperors were added to the design, asserting a kind of dynastic progression of past, present, and future rulers, is not seen on seals. The seal shown above was issued after the coronation of Constantine's son Leo in 751. For more seals of the Isaurian Dynasty see the Dynasties of Empire section.