When Byzantine Emperor Romanos IV Diogenes marched his military into Asia Minor, he thought that he would decisively defeat the Turkish forces and prove to his enemies in the region that the Byzantines, and not the Seljuk Turks, were the preeminent military power. The Byzantine and Turkish forces met at Manzikert on 26 August 1071. The spies employed by Romanos had conveyed to him that the Turkish forces at Manzikert were modest and were led by a minor commander. Romanos thought that they would be easy to defeat. But the intelligence that he had received was flawed—the Turkish forces at Manzikert were under the personal command of Sultan Alp Arslan (who had established himself as the leader of Sunni Islam in Asia Minor) and were part of the main Turkish army.
The Byzantines were employing a significant number of mercenaries and Anatolian levies who fled when the Seljuk Turks began their onslaught. The professional Byzantine soldiers tried to put up a stand. They managed to inflict heavy casualties on the Turkish forces but they were eventually overwhelmed by the superior fighting tactics of the Turks. Romanos himself was injured and captured. When he was brought before Sultan Alp Arslan in a disheveled, bloodied, and tattered state, the Sultan could not believe that the exhausted man who was barely able to stand before him was the Emperor of the great Byzantine Empire (which was then known as the Roman Empire). According to one famous account, Arslan placed his boot on Romanos’s neck and forced him to kiss the ground. This is the exchange that took place between them:
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."
Romanos and the survivors of his army were set free by the Sultan. But a great damage had been done to the prestige of the Byzantine Empire. As the news of the defeat of the Byzantine army and the capture of its Emperor spread through the Levant, there was a panic among the orthodox Christians. They realized that in Asia Minor they were no longer safe. They started fleeing towards Constantinople, which they thought was the only place where they could be safe from the Turkish raids. The influx of refugees put a strain on the economy of Constantinople. There was massive inflation—by the middle of the 1070s, the price of wheat had risen by twenty times. The economic meltdown was accompanied by political upheaval. Several leading magnates rebelled and Constantinople was plunged into a civil war.
The neighbors of the Byzantine Empire took advantage of the chaos. With no military to oppose their advance, the Seljuk Turks marched into Asia Minor. Advancing at great speed, leaving a trail of slaughter and destruction in their wake (according to the account by Anna Komnene, written a few decades after the war), they reached the shores of the Bosphorus, and the surrounding areas became exposed to their raids. By the 1080s, the Seljuk Turks had captured an area of 78,000 square kilometers. There was trouble for the Byzantines in Europe too. The Normans started eying the Empire’s western territories. The dynasties in Croatia and Duklja cancelled their alliance with the Byzantines and sought a new alliance with the papal establishment in Rome.