Muawiyah had sent an army under his son Yazid against the Roman Empire as early as 668.

Yazid, reachingas far as Chalcedon, hasd taken the important imperial center Amorion.

Although the city had been quickly recovered, the Arabs had next attacked Carthage and Sicily in 669.

In 670, the Arabs had captured Cyzicus and established a base from which to launch further attacks into the heart of the Empire.

Their fleet captured Smyrna and other coastal cities in 672.

Finally, in 672, the Arabs sent a large fleet to attack Constantinople by sea.

While the emperor, Constantine IV, was diverted by this action, the Slavs had unsuccessfully attacked Thessalonika.

The victories had ended in 674, however, when the first naval siege of Constantinople itself proved to be a catastrophe due to the defender’s effective use of Greek fire, invented around 670 in Constantinople by Kallinikos (Callinicus), an architect from Heliopolis in the Roman Iudaea Province.

Twentieth-century British chemist and historian James Partington will posit that "Greek fire was really invented by the chemists in Constantinople who had inherited the discoveries of the Alexandrian chemical school".

Many accounts note that the fires it caused could not be put out by pouring water on the flames—on the contrary, the water served to intensify or spread them, suggesting that 'Greek fire' may have been a 'thermite-like' reaction, possibly involving a quicklime or similar compound.

Others have posited a flammable liquid that floated on water, possibly a form of naphtha or another low-density liquid hydrocarbon, as petroleum was known to Eastern chemists long before its use became widespread in the 1800s.

'Uqbah is recalled in 674.

When the conquest of the Maghrib west of Tunisia is initiated by his successor, Abu al-Muh'jir Dyn'r, the Arabs must fight semi-settled Berber communities that have developed some tradition of centralized political authority.

The Succession of Dagobert II and Theuderic III After the Death of Childeric II (675 CE)

After the assassination of King Childeric II in 675 CE, two Merovingian kings emerge as his successors:

• Dagobert II, the long-exiled son of Sigebert III, is restored to the throne of Austrasia.
• Theuderic III, another Merovingian prince, is installed as King of Neustria and Burgundy.

This division of power continues the pattern of Frankish territorial fragmentation, as Neustria and Austrasia once again operate as separate kingdoms under different rulers.

1. The Assassination of Childeric II and the Power Struggle

• Childeric II was murdered in 675 CE, leaving a vacuum of power in the Frankish kingdom.
• His death led to factional disputes among the Neustrian and Austrasian nobility, as different factions backed different claimants.
• The Mayors of the Palace, who had increasingly become the true power behind the Merovingian kings, played a decisive role in the selection of successors.

2. Dagobert II Returns from Exile to Rule Austrasia

• Dagobert II, the son of Sigebert III, had been exiled to Ireland as a child by the former Mayor of the Palace, Grimoald the Elder, in an attempt to usurp the Austrasian throne.
• After Childeric II’s death, Dagobert is restored to power in Austrasia, likely with the backing of the Austrasian nobility and the Church.
• His return signals an attempt to reassert Merovingian legitimacy in Austrasia.

3. Theuderic III Installed in Neustria and Burgundy

• In Neustria and Burgundy, the nobility appoints Theuderic III, another Merovingian prince, as king.
• Like many of his predecessors, Theuderic III serves largely as a figurehead, while real power is exercised by the Neustrian Mayors of the Palace.
• His rule marks the continued decline of Merovingian authority, as the aristocracy consolidates power.

4. The Continued Division of the Frankish Kingdom

• With Dagobert II ruling Austrasia and Theuderic III controlling Neustria and Burgundy, the Frankish realm is once again split into competing kingdoms.
• This division fuels ongoing conflicts between Austrasia and Neustria, as both sides seek to expand their influence.

Conclusion: The Merovingian Dynasty in Decline

The events following Childeric II’s death in 675 CE highlight:

• The continued fragmentation of the Frankish kingdom.
• The struggle between the Merovingians and the nobility, with the Mayors of the Palace becoming the real power in the realm.
• The brief restoration of Dagobert II, though his rule will later end in assassination in 679 CE, further weakening Merovingian legitimacy.

As the Merovingian kings grow increasingly weak, their fate will soon be sealed by the rise of the Carolingians, who will ultimately replace them as rulers of Francia.

A revolt within the Avar Empire, precipitated by the creation in the second half of the seventh century of the Bulgarian state in the southeastern Balkans, results in the expulsion of about nine thousand dissidents.

The Muslims besiege Constantinople in 674 and 675, but are again thwarted by the defenders’ use of Greek fire.

Asparukh, one of the sons of Kubrat, is followed by thirty thousand to fifty thousand Bulgars.

He reaches the Danube and, while the imperial capital, Constantinople, is besieged by Muawiyah I, Caliph of the Arabs (674–678), he and his people settle in the Danube delta, probably on the now disappeared Peuce Island.

The Bulgars have meanwhile assumed the role on the Balkan frontier abdicated by the Avars after 626.

The Danubian region, nominally controlled in the seventh century by the Roman Empire, is inhabited by Vlachs (ancestors of the modern Romanians) and very largely by recently arrived Slavs.

The immigration of the first Bulgars into the Balkans overlaps that of the Slavs in the seventh century.

A pagan people of mixed Turkic stock (the word Bulgar derives from an Old Turkic word meaning "one of mixed nationality"), the Bulgars are warriors who had migrated from a region between the Urals and the Volga to the steppes north of the Caspian Sea.

Constantine cannot prevent the Bulgars from crossing, under their khan Asparukh, southward across the Danube, where they conquer or expel the Slavic tribes living north of the Balkan Mountains.

Here, on the plain between the Danube and the Balkan Mountains, the Bulgars establish the kernel of the so-called first Bulgarian empire—the state from which the modern nation of Bulgaria derives its name.

Perctarit had been king of the Lombards from 661 to 662.

The son and successor of Aripert, he had shared power with his brother Godepert.

Perctarit was a Catholic, Godepert an Arian; the former ruled from Milan, the latter from Pavia.

Godepert had requested the aid of Duke Grimoald of Benevento in a war with Perctarit, but the Beneventan had had him assassinated and taken over the kingdom, forcing Perctarit to flee to the court of the Avar khagan Kakar.

However, his wife, Rodelinde and their son Cunipert had been captured by Grimoald and sent to Benevento.

Perctarit had returned soon after to conspire against Grimoald, but fled again to Gaul.

Under Grimoald, the Lombards had successfully fought the Franks and the Romans in Italy.

When duke Lupus of Friuli refused to swear allegiance to Benevento, the king had had the Avar khagan attack him in 663 but after the Avars refuses to leave, Grimoald had had to wage war to force them out.

After Grimoald confirmed a treaty with the Franks, Perctarit had prepared to flee to England, but news of Grimoald's death in 672 had reached him first.

Returned from exile and retaking his realm, which had been ruled on behalf of Grimoald's son Garibald, Perctarit had made Catholicism the official religion, but did not recognize papal authority.

He has forced Lombard’s Jews to adopt Christianity or be killed; many survive by outwardly accepting Christianity.

The Lombards take Taranto from the Empire in 675.