Alexios I Diogenes (Latinized as Alexius I) was the Byzantine emperor from his coup against his sister, Anthemia, Queen of Greeks, to his death in 1132. The Byzantine empire was brought to what was at the time the empire's height, earning him the conqueror.
Alexios was born as Alexios Lascaris into a wealthy noble family in Smyrna in 1078. His father participated in the Third Norman Invasion of the Balkans, engaging the Normans in Corfu, where he became deceased. The death of his father broke him, and this was made worse when his mother ditched him when she traveled to Trebizond, marrying a Pontic nobleman.
With him losing his parents, Alexios made the trip for Constantinople. The trek was harsh, and he had to extend his trip after he couldn't be ferried against the Bosphorus Strait. He headed to the Dardanelles, crossing the strait, heading for Constantinople, where he sought the adoption of Basalieus Nikephoros III.
Nikephoros accepted him warmly, becoming a favorite of the emperor. Being much older than his first-child, Calixtus, and being more favored by Nikephoros, the emperor declared him heir apparent to the Byzantine throne This did anger Calixtus, but his complaints were promptly dismissed.
Alexios participated in his father's military campaigns. He showed himself to be a great warrior and general, exhibiting extraordinary military and tactical skills. This only reinforced his status as an heir, as this was exactly what Nikephoros wanted: a strong, capable leader that was skilled in the art of war. Whenever Alexios returned to the Great Palace of Constantinople from a campaign, crowds of people showered him and his father with praise.
As the future emperor of the Romans, Alexios believed that he should tour Rome for reasons that are lost to history. Some claim he was attempting to strengthen relations with the papacy after half a century of animosity, while others state that he longed for a Byzantine reconquest of Rome. Regardless, while on his way, he met Housse de Montfault, the daughter of a particularly wealthy Norman noble. Soon afterward, he arranged a marriage with her after returning from Rome.
News reached Constantinople and the Byzantine court was not amused. Nikephoros had allowed the marriage, even hastily proposing that a proxy marriage be arranged, as he saw a Byzantine-Norman marriage as a way to improve relations with the Norman Kingdom of Sicily. However, the Byzantine clergy was infuriated as Housse was a westerner, a Latin. The Byzantine Church Bureaucracy at this time was becoming increasingly and frivolously anti-catholic, and although the height of this anti-catholic sentiment would not be reached in the 17th century under the reign of Empress Apollonia, it was still strong enough for the clergy to object to anything that didn't harm a catholic.
Nikephoros was intimidated by the sheer power and influence of the Byzantine clergy and thus when they demanded that Alexios be disinherited, he reluctantly obliged. Instead, Calixtus was elevated to the status of an heir. Alexios was infuriated, but accepted his fate.
After he lost his status as heir to the Roman throne, Alexios temporarily vanishes from historical records until 1113, when it is documented that Alexios was invited to a rendezvous by members of the Byzantine nobility. By now, Calixtus, the child general, had died while fighting in Armenia, and his sister, Anthemia, was now empress. She was unpopular with the Byzantine nobility due to her detested land reforms that made the nobles feel as if their rights were getting encroached on. They were aware that Alexios was furious over his delegitimization and speculated that he still longed to be emperor of the Romans.
A conspiracy was formed against the empress. More and more nobles received word of this plot and joined the cause.
Finally, in 1114, Alexios instigated the coup d'etat, overthrowing her half-sister. On April 18, Alexios was coronated as Emperor and Autocrat of Romans.
After the exiled Anthemia to Rome, Alexios, though barely six months into his reign, Alexios already began prepping for war.
Conquest of Assyria and Syria
Byzantine foreign policy was based around the defense of the empire from the South Slavs in the Northwest and the defense of the Muslims in the south and east. With the former being expelled up to the defensible Danube River, the Byzantines satisfied their thirst for war with the latter.
Alexios selected Assyria, a large, wealthy state that was also a formerly Seljuk territory. It was exceptionally peaceful and friendly, a sharp contrast to the warring Seljuk beys of Persia. Alexios designated it as the empire's target, and invaded in October, 1114.
The conflict initially was fought with ease. However, the Fatimid Caliph, Al-Amir Bi-Ahkamillah, was wary of further Byzantine expansion of power and influence. Thus, he intervened in the conflict, allying with the Assyrians, and the war came to a standstill. After several years of conflict, the Fatimids were repelled at the Battle of Kirkuk. This cemented the perception of Alexios as an enormously skilled military skill, as it was a decisive Byzantine triumph The defeat humiliated the Fatimids and forced them to withdraw from the conflict, allowing for the Byzantines to focus on conquering Syria in 1117.
Alexios schemed to invade the Fatimids once more, but for now, he was faced with a new task: consolidating his gains. This process was accelerated considerably by the fact that large amounts of the local population were Christian who swore their allegiance to the emperor in Constantinople. Alexios capitalized on this fact, elevating the Christian population to test the status of nobility and granting them numerous liberties. By the mid-1120s, the region had been fully integrated into the Byzantine realm.
In 1123, the Byzantines crossed the Byzantine-Fatimid border. There goal: the conquest of Syria. The Byzantines and Fatimid engaged each other at the Battle of Palmyra, which was a decisive Byzantine victory, and a pivotal moment in the conflict.