The mid 11th Century marked the high water mark of the Byzantine Empire, after it’s recovery from the loss of much of its territory during the initial Muslim conquest of the 7th and 8th Centuries. At that point, the Byzantine Empire stretched from Dalmatia in the west, incorporating the whole of the Balkans, to Antioch in Syria in the south, and all of Anatolia to Armenia in the east.
The recovery of the Byzantine Empire was matched by the relative decline of the Abbasid Caliphate, a Sunni Mulsim dynasty that ruled much of the Middle East from Baghdad. Unfortunately the decline of the Abbasids meant that the Caliphate was no longer an effective bulwark against Central Asian nomadic tribes, such as the Sejuk Turks.
In 1040, the Sejuk Turks invaded the Abbasid Caliphate from the east, in which is now Iran. The Sejuk Turks quickly overran Iran and Iraq, penetrated Armenia, and ravaged Anatolia (modern Turkey) as far as the Byzantine Black Sea port of Trebizond by 1054. The next year, by 1055, the Sejuk Turk ruler Tughrul became Sultan, taking Baghdad as his capital. The Sejuk Turks, like many nomadic peoples before and since, had suddenly found themselves the rulers of an empire.
The onset of the Sejuk Turks coincided with a period of dynastic struggle in the Byzantine Empire that tended to strengthen the hand or the former and severely weaken the latter. This allowed the Sejuk Turks to consolidate their hold on Armenia and to raid throughout Anatolia with impunity. Byzantine mercenary infantry was also too slow to catch the speedy and nimble Sejuk Turk horse archers.
Finally, in 1071, the Byzantine Emperor Romanus IV resolved to deal with the Sejuk Turk threat once and for all. He marched east with a polygot army that likely numbered forty thousand men. This army consisted of ten thousand native Byzantine troops, Frankish and Norman mercenaries, Turks, Bulgarians, Pechnegs, Armenians, and a detachment of the Varangian Guard, a unit of Norse mercenaries.
Romanus’ main goal was to take back the Byzantine fortress town of Manzikert, in eastern Anatolia, recently taken by the Sejuk Turks, and to force the Sejuk Turk army into a general battle. The march across Anatolia was slow, due to the difficult terrain, the size of Romanus’ baggage train, and the tendency of some of the mercenaries, especially the Franks, to plunder the local population.
The Byzantine Army arrived at the town of Theodosiopolis (modern Erzurum) in June. After some arguing among the generals whether to consolidate their position or march on, the Byzantine Army marched on, toward Lake Van, hoping to retake Manzikert quickly, under the impression that the Sejuk Turk Army was at some distance away.
At this point, Romanus decided to split his army in two. John Tarchaneiotes took twenty thousand men toward the fortress of Khliat, while Romanus took the other twenty thousand to Manzikert. It appears the John Tarchaneiotes encountered the Sejuk Turk Army, under the Sultan Alp Arslan, and promptly fled. He finally surfaced at Melitene in South Eastern Anatolia and did not take part in the battle.
On August 23rd, Romanus took Manzikert easily. The next day, some foraging parties made contact with the Sejuk Turk Army. A cavalry force under the General Basilaces was sent out and was annihilated. On August 24th Romanus and the Sejuk Turks skirmished, with the result that Romanus’ Turkish mercenaries deserted to the enemy. On August 25th, Alp Arslan attempted to negotiate a peace, but the embassy was rejected by Romanus.
On August 26th, the Byzantine Army arrayed for battle. The left wing was commanded by Bryennius, the right wing by Theodore Alyates, and center by the Emperor Romanus himself. There was a reserve force under Andronicus Ducas, Romanus’ rival for the throne of Byzantium. The Sejuk Turks were arrayed in a crescent formation about two and a half miles from the Byzantine formation.
The Byzantines advanced, while the Sejuk Turks gave way, the center retreating, the wings of the crescent closing on the Byzantine flanks. Despite constant attacks by the Sejuk Turk horse archers, the Byzantines managed to take the Sejuk Turk camp. However, the hit and run tactics of the Sejuk Turks were beginning to tell against the Byzantine flanks, Romanus ordered a retreat.
It was a disaster, as the Byzantine right wing was confused by the order and the reserves, under Ducas, essentially abandoned the rest of the Byzantine Army and withdrew rapidly to the Byzantine camp. Al Arslan attacked, routing the Byzantine right wing, then the left. Romanus was wounded and taken prisoner.
Sultan Alp Arslan treated his prisoner with great courtesy, offering him generous terms, then having him escorted back to the Byzantine camp, loaded with presents. Thus ended the Battle of Manzikert with a decisive Sejuk Turk victory.
Romanus was soon deposed, blinded, and exiled to an island where he soon died. Despite the fact that Manzikert did not immediately, the battle meant that Byzantium had lost most of Anatolia. Because of the dynastic struggles that followed, the Byzantines were unable to put an effective army in the field for many years, allowing the overstretched Sejuk Turks to consolidate and extend their power. Manzikert was also one of the contributing causes of the Crusades, since the Sejuk Turks took Jerusalem and began a policy of antagonism against Christian pilgrims.
Manzikert did not make the ultimate fall of the Byzantine Empire inevitable. But the Byzantines never seemed to recover from the blow, which was both physical and psychological. The Byzantine Empire was thus unprepared for the challenges to come, such that their decline became inexorable, even though Byzantium lasted almost another four hundred years.