John III, Byzantine emperor of Nicaea

John III, Byzantine emperor of Nicaea (John Ducas Vatatzes) (d´ks vtt´zz) (KEY) , d. 1254, Byzantine emperor of Nicaea (1222–54), successor and son-in-law of Theodore I. He extended his territory in Asia Minor and the Aegean islands but failed (1235) to take Constantinople from the Latins, although he was aided by Ivan II of Bulgaria.

Subsequently Ivan, the Cumans, and the Latins of Constantinople allied themselves against John, who held his own. John joined the Turks against the Mongol invaders. He annexed Salonica (Thessaloníkai) in 1246 and reduced the despotat of Epirus to vassalage, thus nearly recovering the territories of the Byzantine Empire.

He maintained close relations with the German emperor, Frederick II, whose daughter he married. During his reign the empire flourished. He was succeeded by his son Theodore II. The city of Niceaea was built on an important crossroads between Galatia and Phrygia, and thus saw steady trade. It appears to have lost some of its importance during the early Roman era a few hundred years later, but this changed dramatically with the split of the empire into west and east.

The eastern half, later known as the Byzantine Empire, made the city an important defensive stop to the south of Byzantium (Constantinople). Much of the existing architecture and defensive works date to this time, early A.D. 300s.

Major earthquakes struck in 358, 362 and 368, ruining much of the early city's architecture. It was during this time that the early Christian leaders met in Nicaea in 325 under the direction of Constantine, in what would later be known as the First Council of Nicaea, the first of many Ecumenical councils.

They met to consider the issues of Arianism, resulting in the current concept of the Trinity and the creation of the Nicene Creed. The church of Hagia Sophia was built by Justinian I in the middle of the city in the 6th century (modelled after the larger Hagia Sophia in Constantinople), and it was there that the Second Council of Nicaea met in 787 to discuss the issues of iconography.

About the featured coin: EMPIRE of NICAEA. John III, Ducas-Vatatzes. 1222-1254. AV Hyperpyron ( 4 grams). Magnesia mint. IC XC across field, Christ, nimbate, seated facing on throne, raising hand in benediction, holding Gospels / [IW DECPOTH TW PORFUROGENNHTWN], standing facing figures of John, wearing crown and loros, holding labarum and akakia, and the nimbate Virgin Mary, who crowns John; cross of dots on Virgin's cloak.