Second Rashidun Caliph, Amir al-Mu'minin, Asad Allah. (644-684)
Part 2
Hadith of Conquest Fulfilled
“Verily, you shall conquer Constantinople. What a wonderful army will that army be, and what a wonderful commander will that conqueror be.”
In preparations for the siege, forces had been gathered in Crete, Rhodes and other islands of the Aegean that had been captured either recently or back during Khalid's campaigns. Even if Mu'awiya had been imprisoned, his aspirations for the Caliphate to build a powerful navy were slowly being fulfilled. On the other hand, Ali arrived at Nicomedia in February of 656 with a sizeable force of 10k men, which were to be added to Khalid's gathered force of 40k. Clearly, gathering such a force wouldn't be easy to hide from the Roman Emperor, who was sitting very close to them at Constantinople. Phocas II received the letter from one of his courtiers and was frightened at the prospect of already losing his empire. He sent a letter to Kubrat, in hopes that the Bulgars would once again come to the aid of the Romans. This letter, however, never reached Kubrat as he had already died.
For the past few years, things had been in turmoil at Constantinople. Even if the siege of Constantinople of 642 had been unsuccessful, the questions of how much longer would the walls resist, or how much longer will the empire itself survive, plagued the minds of the inhabitants of the city. Ever since his coronation after the assassination of Heraclonas, Phocas II had not made a single move to try and fight back against the Caliphate. It seemed as though he was uninterested with the fact that Rome had been reduced to almost half of its former territories and now they had the enemy knocking at their door. The letter in which the news of an incoming second siege was only the straw that broke the camel's back. Only a week after the letter was received, Phocas II was assassinated in his chambers while sleeping by an unknown assailant. It is speculated that it had been Leontius, his brother, who then became the regent of Constantine III, his nephew. Constantine III was merely a teenager, and Leontius wasn't really much different from his brother.
One thing in which he differed from Phocas II, however, was in that he at least looked for support in the incoming defense of Constantinople. He offered absurd amounts of gold to several slavic tribes and the Avars, who accepted the deal and began heading to the capital of the Romans. The catch in this deal was that Leontius didn't have such amounts of gold. In fact, the Eastern Roman Empire hadn't possessed such amounts of gold ever since the rule of Anastasius. Leontius was willing to do anything to defend the city and that included risking to get even more enemies other than the Arabs.
The invasion from Nicomedia was launched in March of that year, and an initial Roman force of 5k men met the Rashidun army in the outskirts of the capital. Normally, as per Khalid's usual modus operandi, a battle would have started and the small Roman force would have been wiped off the face of the earth by the Rashidun army, which was 10x its size. However, Ali was there, and so he ordered no violence to ensue and negotiated with them. His offer was simple: accept Islam and join the Caliphate, or be captured and killed in case of resistance. The size of the Rashidun army was intimidating, and so most of those 5k troops took Ali's offer and joined their side. Around 500 resisted and were captured after a short fight.
The army reached the asian side of the Bosporus in slightly over a week. Chrysopolis barely had a garrison that the Rashidun army easily overwhelmed. After that, they only had to wait for the navy to arrive at the Bosporus. Many began to flee from Constantinople as early as the fall of Chrysopolis, both to mainland Greece, the few remaining territories of the empire in Italy and to the city of Rome itself.
The Rashidun navy arrived at the strait after a few days, and most of it immediately engaged in battle with the Roman navy. A small group of three ships split from the main navy and intercepted a series of smaller, commercial ships that were reaching Constantinople. They were several refugees from places like Syria, Jerusalem and Egypt. Among them was a man named Kallinikos, who offered to share some secrets in exchange for his own safety and that of his fellow refugees. Initially, his request was to be ignored, but as his story reached Ali, it was fulfilled and he was taken to the Caliph himself. After a meeting, Kallinikos was taken to Medina. Ali stayed at Chrysopolis, though, as the Second Siege of Constantinople began.
While the naval battle raged on, the Slavic and Avar reinforcements arrived on the european side of the City. They were initially mistaken as enemies, but eventually they were told by Leontius that they were the reinforcements and the gates of the walls were opened for them. The Avar Khan, Bayan IV, was among them. He marched through the city and met Leontius and Constantine III at the palace. The Khan was not happy with the preemptive attack launched at them in the walls for mistaking them for enemies, but the regent made sure to calm tensions down by reminding them of the rewards for their collaboration.
Days and weeks passed and the Rashidun navy failed to break the Roman defense. Abd al-Rahman ibn Abi Bakr and Khalid ibn al-Walid were then put at the head of an army of 30k that was to go back and cross the Hellespont. Once at Abydos, Abd al-Rahman and Khalid marched into Thrace, and finally reached Constantinople by 657. Their arrival finally allowed for the total isolation of the city, as they were surrounded on all flanks. And to increase the psychological effect, Khalid reused an old trick of his. He divided the armies and gave each commander different banners. They marched and arrived at the camp established just outside the walls at different times. This strategy had previously tricked the Romans in the Battle of Mu'tah into thinking that the Muslim armies were receiving reinforcements, and it did here. This way, whenever Khalid's men tried to attack the walls, the Romans would be a lot more chaotic in their defense due to their fear.
This was complemented by the building of a double siege wall of stone, which solidified the isolation of the city. This was the situation that was maintained for a year until mid 658. Thrace and the entirety of Asia Minor had been captured by the Caliphate, while Constantinople itself was entirely isolated except for the fleet that still somehow protected its ports. Its inhabitants were starving, and the Avars and Slavs grew more unsatisfied. In July of that year, Bayan IV overheard a conversation between Leontius and one of his commanders, in which he revealed that he did not have the gold to pay the mercenaries. This provoked the Slavs and Avars to take over the city. Bayan captured the palace and killed all the guards and Leontius. He held Constantine III hostage, so as to use the kid as a puppet.
Priscus, son of Leontius, escaped the massacre and reached the Theodosian Walls. There, he requested for the gates to be opened. He was told it was insanity since Khalid was currently carrying out an attack just outside. Priscus then bribed some of them and killed those who opposed him. They opened the gates, thinking they'd be spared by the Arabs and that they would wipe the Avars. However, the first to be wiped out were the guards of the walls, and among them was Priscus.
Khalid led a swift and violent charge into Constantinople. The surprised Roman, Slavic and Avar troops were unable to properly organize and so were progressively divided into smaller groups as they were massacred.
On the opposite side of the city, news of the opening of the Theodosian Walls spread very quickly. Most of the navy got a few refugees from the ports and then left for Cherson and Theodosia at Crimea. The Rashidun navy crushed those who were too slow and then helped Ali and his army to cross the Bosporus. From the ports, the other half of the Rashidun army began charging into Constantinople. Very swiftly, Ali captured the Palace, the Hippodrome and the Church of Hagia Sophia. He clashed against the Avar Khan right in front of the Palace, who lost his life during the battle. The desperate Slavic and Avar troops dispersed and tried to escape. Eventually, though, all were captured.
A group of Greek aristocrats grabbed the young Constantine III during the chaotic battle outside the Palace and escaped the city on a ship to Greece. It is said they bribed one of the Arab ships, given that there would be a naval blockade ongoing. Ali was disappointed to not meet the Roman Emperor once he entered the Palace, oblivious to the fact that Constantine III was a mere teenager.
Khalid and his troops met with Ali's at the Capitol. Hasan ibn Ali was not happy when he noticed that Khalid and his men were capturing civilians and looting their houses, but nothing was made of the issue. When the Sayf Allah met the Caliph, it was proclaimed that the Hagia Sophia would become the Church of Khalid ibn al-Walid, in honor of his important part in the victory. It is also theorized, however, that Ali made this to keep Khalid happy, as his popularity was starting to get out of hand.
With Constantinople captured, the Roman Empire had been reduced to a bunch of scattered provinces with very few military forces. The Exarchate of Africa almost immediately declared independence again, even though 'Amr and his troops were already raiding towns on the border. As for Greece, the several provinces began to split as the succession became controversial. Constantine III was initially taken to Athens, backed by the patricians that saved him. However, they were not successful as people either did not believe them or did not have a good opinion of Constantine. For such, they were forced to leave to the italian territories of the empire, as anyways the invasion of Greece seemed imminent. Initially, the Patricians and Constantine arrived at Syracuse, and from there they sailed for Rome. There, he would meet Pope Vitalian, who would support him as the legitimate Roman Emperor.
As for the Caliphate, their plans of continuing their campaign into Greece were delayed due to a massive uprising at Persia. In almost all the Iranian provinces, separate rebellions rose against the Caliphate. This forced Ali to go back, and he took Khalid, as well as Hasan and Husayn, with him. Abd al-Rahman ibn Abi Bakr was left in charge of the garrison of Constantinople. There, he ransomed the new Avar Khan, who had fought alongside his father, and some of his troops. Abd al-Rahman also oversaw the conversion of many of the captured Slavs, who joined the garrison of the city alongside a few Greek converts (who were a lot less).
By the time Ali had arrived at Ctesiphon, several rebel armies had connect at Khorasan, and they were said to be led by Yazdegerd III. This prompted a very strong and heavy response from the Rashidun army, that clashed in Merv with the rebel armies. They crushed the rebels and found out that, in fact, Yazdegerd had died years prior on his way to China. The rebel leaders were captured, which allowed Ali and his sons, Hasan and Husayn, to return to Medina, where he met the rest of his family and the Majlis ash-Shura. Khalid, on the other hand, returned to Constantinople, where he married the daughter of an aristocrat.
Conquest of North Africa
During Ali's return to Medina, he sent a letter to Abd-Allah ibn al-Zubayr, in which the further invasion of North Africa was greenlit. Abd-Allah and Amr left Fustat and marched to Barqa, which they besieged and captured in 660. The next stop was Tripoli, which the Rashidun army reached and besieged from 660 to 661, when the city gave in to starvation. From Tripoli, the march continued to Sufetula. There they met a bigger resistance, which was crushed nonetheless and the city was captured. By 662 almost all of the Exarchate of Africa had fallen to Muslim hands thanks to the unwillingness of the local people to continue fighting.
Gennadius, the exarch, held on to power at Carthage with the few supporters he still had. The city was completely surrounded in 663 by Abd-Allah and 'Amr, who gave him the option to give up and pay tribute to them. The exarch refused and chose to continue fighting. This resulted in a catastrophic defeat and the total razing and looting of Carthage. Gennadius was executed as were his generals.
And with Carthage, most of the Roman Empire had now been annexed by the Rashidun Caliphate. With Khalid capturing the remnants of Roman presence in Greece, there's only one place left to go: further into the Maghreb.