In its approximately 1000 years of history the Byzantine Empire had suffered a number of military disasters. It survived the loss of Egypt, Syria and North Africa to the Arabs. It fended off multiple sieges of Constantinople by the Persians, Arabs, Bulgars and other tribes. The Empire survived the Slavic migration into the Balkans in the 6th century. It survived the defeat and death of the Emperor Nikephoros I at the hands of the Bulgars in 811 AD. Each time with the Empire on the verge of collapse a new ruler or dynasty would revive imperial fortunes. The most spectacular revival came during the long reign of the Macedonian Dynasty (867-1056 AD). Taking advantage of the disintegration of the Abbasid Caliphate Byzantine arms pushed into Syria and recovered Armenia. The military glory culminated in the reign of Basil II the Bulgar Slayer who eliminated the First Bulgarian Empire and restored Byzantine rule over the Balkans. Through the marriage of his sister Anna to Vladimir I of Kiev he completed the Christianization of the Rus and spread Byzantine culture into that region.
It was not to last. Basil II died unmarried and childless in 1025. His weak successors lacking his military ability starved the army of funds. Palace coups to seize the crown became the norm in the next 50 years. Gradually the hard fought military frontiers began to crumble. The remnants of Justinian’s conquests in Italy were gradually whittled away starting in the 1040s. The Pechenegs started raiding the northern frontiers and gradually the frontiers in Asia also came under attack.
When disaster struck in 1071, the Byzantine Empire was having one of its depressingly frequent bouts of instability. Emperor Romanos IV had ascended the throne by marrying the widow of his predecessor Constantine X Doukas and placing her children under his protection. The rest of the Doukas clan resented the interloper and their loss of power and were as events showed waiting to stab the Emperor in the back.
Romanos had been chosen to deal with a pressing military crisis in the east. For the preceding century the Turkish tribes from the steppes had been pouring into Iran and Iraq and had reduced the once mighty Abbasid Caliphate to vassalage. By 1067 the Seljuk Turks had captured Armenia. Even though the Turks were ready for a truce since they were more interested in attacking their schismatic religious rivals the Fatimid Caliphate in Egypt, the Emperor decided to attempt retaking Armenia.
After a long exhausting march across Asia Minor the Emperor decided to take the fortress of Manzikert. The Byzantine Army was not the disciplined army of Basil II and was full of mercenaries and scheming noblemen. Even worse the Emperor had no idea that the Seljuk Sultan Alp Arslan was close by. The Turks on the other hand were aware of Byzantine troop movements. Unaware of the presence of the Turks the Emperor split his army of 70,000 in half sending a detachment to attack Khliat while he proceeded to Manzikert. This detachment appears to have been destroyed and at any event played no further part in the coming disaster. On August 23 the Emperor retook Manzikert but discovered Seljuk troops close by. By August 25 it was clear this was the main Seljuk army. Rejecting a final peace embassy, the Emperor decided to fight a battle and crush the upstart Turks once and for all.
The Battle of Manzikert was a confusing affair. While the center occupied the Seljuk camp the left and right wings were harassed by the hit and run tactics of the Seljuk horse archers. Unable to force a battle the Emperor decided to withdraw at the end of the day. This gave Andronikos Doukos who commanded a detachment on the right an opportunity to betray the Emperor. Rather than covering the withdrawal he marched back to the camp at Manzikert. This threw the Byzantines into confusion giving the Seljks a chance to attack. The remainder of the right wing was destroyed, the left wing fled. The Emperor in the center was surrounded, wounded and captured.
The captured Emperor was brought before the Sultan Alp Arslan where the conversation below between the two rulers allegedly took place:
Alp Arslan: “What would you do if I were brought before you as a prisoner?”
Romanos: “Perhaps I’d kill you, or exhibit you in the streets of Constantinople.”
Alp Arslan: “My punishment is far heavier. I forgive you, and set you free.”
Yet even with total victory, the Seljuk Sultan was anxious to attack the Fatimids and offered the Byzantines generous terms. The treaty left Anatolia source of much of Byzantine military manpower intact and the Emperor was released on the promise of an annual ransom.
Manzikert did not have to be the seminal defeat in the history of the Byzantine Empire. Much of the Byzantine army and generals were safe. The Turks had moved on to other plans. But what happened next is what resulted in the eventual collapse of Byzantium.
The traitor Andonikos Doukas marched back to Constantinople and proclaimed Romanos’s stepson Michael VII as Emperor and Romanos deposed. The unfortunate Romanos was blinded and died a painful lingering death when the wound became infected. The scholarly Michael VII proved unfit for the situation. Court intrigues and attempted coups became common. In the ensuing decade with Constantinople distracted by civil war the Byzantine position in Anatolia collapsed. By the time Alexios I Komnenos seized the throne in 1081 almost all of Anatolia was lost to the Turks and Byzantium was no longer able to protect pilgrims to to the Holy Land.
This eventually led to the famous appeal to the Pope for help, resulting to Alexios’s unpleasant surprise in the First Crusade. Alexios, his son John II and grandson Manuel I were able to recover the coastal strip of Anatolia. However the Komnenian restoration never recovered the Anatolian heartland and were unable to expel the Turks from the region. The Turks would resume their advance in the 13th century (after Byzantium was further weakened by the Fourth Crusade) and would eventually drive the Empire entirely out of Anatolia.
It was not obvious at the time, but Manzikert due to its aftermath turned out to be one of the most pivotal battles in history.