Constans II and Constantine IV, Miliarense of "Ceremonial silver coinage" (silver eplica) 641 - 668 AD.
OBV: DN CONST C CON(ST), Facing busts of Constans and Constantine.
R: Cross on globe above three steps. No legend.
Extremely rare coins!

From Wikipedia, the free encyclopedia:

Constans Heraclius, known in English as Constans II, (November 7, 630–September 15, 668) was Byzantine emperor from 641 to 668. He was the son of Constantine III, and due to the rumours that Heraclonas and Martina had poisoned Constantine III he was named co-emperor in 641.

Under Constans, the Byzantines completely withdrew from Egypt, and the Arabs launched numerous attacks on the islands of the Mediterranean Sea and Aegean Sea. Constans sent a fleet to attack the Arabs at Finike in 655, but was defeated; the Arabs were preparing to attack Constantinople, but didn't carry out the plan when civil war with the Shiites broke out among them. In 658 he defeated the Slavs on the Danube River, temporarily slowing their advance throughout the Balkans.

He wanted to avoid the succession problems of his own reign, so he had his brother Theodosius murdered and named his sons Constantine, Heraclius, and Tiberius co-emperors. In 661 he campaigned against the Lombards in Italy and reportedly decided to move the capital of the empire to Syracuse, in east Sicily. This proved to be a very unpopular decision. On September 15, 668 Constans was assassinated in his bathroom by his chamberlain. Constantine succeeded him as Constantine IV.

Constantine IV (649-685) was Byzantine emperor from 668-685. He had been named a co-emperor with his father Constans II in 654, and became emperor when Constans was assassinated in 668.

The most immediate threat to the empire under his reign were the Arabs, who sent a fleet to attack Constantinople by sea in 674. While Constantine was diverted by this, the Slavs attacked Thessalonika.

Constantinople survived the Arab siege until 678, when the Byzantines employed Greek fire against the Arab fleet at the Battle of Syllaeum. This was one of the first times Greek fire was used in combat. The Arabs withdrew, and were almost simultaneously defeated on land in Anatolia.

In 680 Constantine called the Sixth Ecumenical Council (also known as the Third Council of Constantinople), reaffirming the doctrines of the Council of Chalcedon in 451. This solved the controversy over monothelitism; conveniently for the empire, most monothelites were now under the control of the Arab caliphate.

In 681, Constantine was forced to acknowledge the new Bulgarian Empire in the Balkans after having suffered a disastrous defeat in 680.

His brothers Heraclius and Tiberius had been crowned with him as Augusti at the demand of the populace, but in 683 Constantine had them mutilated so they would be ineligible to rule. This ensured the succession of Justinian II when Constantine died of dysentery in 685.