I've heard various arguments that the Byzantines were dealt the mortal wound at Manzikert in 1071 which allowed the Turks to claim most of Anatolia and set the stage for the later sacking of Constantinople by the Latin Crusaders. I've also heard that the it was the sacking itself that set the Empire on a course to its ultimate end. With the fall of Constantinople in 1453 being generally accepted as the end of the Byzantine Empire proper; when did the slope toward that end begin?

  • I changed the tag 1400s to 15th-century. See here
    – Daniel
    Oct 13, 2011 at 17:25
  • The decline of Byzantium was not irreversible until quite late, if then. Had Byzantium made different choices -- in politics, in battle -- or had their enemies made different choices, the outcome could have been very different. Inevitability only happens when no choices by either side can affect the final outcome. Consider, for example, the Turks choosing to move south into Arab lands, or several fortuitous Turkish civil wars, or Enrico Dandolo dying young. This is basically a meaningless question.
    – Mark Olson
    Jan 19, 2023 at 16:07
  • Well according to my thorough and expansive research with the Europa Universalis series, there is no point at which the Byzantine Empire couldn't have rebounded to conquer the world until around 1454.
    – lly
    Jan 20, 2023 at 14:18
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    Bringing the above point back to reality, you do have to want it and you have to make the right societal choices to make it happen. The aristocracy in Byzantium were extremely powerful and plenty of them made separate peaces and side deals in their own interests with the Venetians, the Genoese, the Turks, &c. Sure, there are some people (mostly the poor) who would go to the walls for the Theotokos but there are plenty (including most of a sophisticated cosmopolitan upper class) who are perfectly fine with praying 5 times a day so long as most of their deeds and contracts stay valid.
    – lly
    Jan 20, 2023 at 14:21

9 Answers 9


The Fourth Crusade was the turning point. The crusade was high-jacked by Venice to take revenge on the Byzantines for past deeds: imprisonments, break of contract, etc... The crusade was aimed to land in Egypt originally, as it was seen as the main threat to taking Jerusalem back. However, since the crusaders could not pay for the large Venetian fleet, it was arranged that they would do a few missions for Venice first. Not all crusaders agreed, but the majority saw no choice. Even the Pope was unhappy with this state of affairs.

So, once Venice took control of Constantinople, a series of civil wars and coup happened. This weakened Byzantium to the point where it could not recover. From there on, it was just a matter of time before another power took control.

As a side note, the Byzantine fleet was in great part responsible for the might of the empire. Once the Empire gave this to Venice to build and use, it was just a matter of time before the fleet degraded beyond the local ability to rebuild it. An example of why out-sourcing is bad.

Source: John Julius Norwich: History of Venice, History of Byzantine Empire.

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    This is a very common argument (perhaps the most common). I personally have trouble with it because the city didn't fall to the Turks for another 250 years. That's a pretty dang long time. Longer than the USA has existed. But again this is the argument many scholars stand by.
    – T.E.D.
    Jan 19, 2016 at 14:37
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    @T.E.D. That is a fair comment. The justification is that after the fourth crusade, the Byzantine Empire was (more or less) in constant decline. It never really recovered from it despite it taking a long time to finally collapse. Jan 19, 2016 at 14:51
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    Well...it recovered a bit. Just not enough. But the Turks still couldn't take the city walls until they brought in newfangled canon, so perhaps gunpowder deserves the credit instead? Within 2 generations these same Turks held all SE Europe up to the gates of Vienna. So perhaps the Turks being badasses had something to do with it too? Again, I personally don't think its quite this simple, but this is the common position, and you put it forth well, so I don't begrudge the checkmark either.
    – T.E.D.
    Jan 19, 2016 at 14:58
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    Opposite point to TED: This is a very common argument and so is his. The go-to for the late turning point—which he doesn't mention—would 1354, the fall of Kallipolis/Gallipoli to the Turks, which surrounded the Romans and made everything basically hopeless. Personally, I'll go with you both being wrong. It's still Manzikert, which was the reason the empire got in hock to the Venetians in the first place and was weak enough to strong-arm.
    – lly
    Jan 20, 2023 at 14:26
  • @Ily Mantzikert was a defeat but how did it lead the Byzantine Empire to fight the Venetians? Still these two forces fought for trade control and sea power? Jan 30, 2023 at 19:44

I don't think it is possible to idenitify a single point in history as beginning the "slope toward the end". Such thinking results from the simplistic model of an empire's history as consisting of two segements: "growth" and "decline". In reality, the history of the Byzantine empire is a complex sequence of alternating growth and decline.

I'd say that the first high point of the empire was the end of Justinian's rule, when the borders of the Byzantine empire bore some resemblance to the old Roman empire. A large numbers of events weakened the empire from this high point. They include the loss of much of the Italy to the Lombards in the 6th century and the gradual loss of Levant, Mesopotamia and North Africa to Muslim Arabs starting from the rise of the Umayyad Caliphate in the 7th century.

The Emperor Basil II's rule marked a strengthening of the empire, when the First Bulgarian Empire was destroyed in 1014 and Kievan Rus' accepted Byzantine-style Christianity.

In 1054 the Byzantine Church formally split with the Church of Rome, after a long period of growing tensions. The cause of the tensions was a combination of political rivalry between the Byzantine Emperor and the Pope and religious divergence due to movements such as Monophysitism, Monothelitism and Iconoclasm within the Byzantine Empire. This eventually contributed to the demise of the Empire due to its religious and therefore political isolation. Territorial decline continued with the loss of of remaining Italy to the Normans in the 11th and 12th century and the gradual Seljuk takeover of Anatolia starting in the 11th century.

Another high point was the Komnenian restoration in the 12th century, during which much of Anatolia was temporarily recovered. After that, there was return to severe dynastic strife which was another major factor in Byzantine decline.

During the Fourth Crusade, Constantinople was taken by the (Roman Catholic) crusaders in 1203. The key role in this event belonged to the naval–commercial rivalry between the Byzantine Empire the Republic of Venice. The crusaders couldn't pay for the fleet Venice supplied them and agreed to attack Constantinople as a compensation. The fall of Constantinople caused the split of the Empire into three parts: Empire of Nicaea, Empire of Trebizond and the Despotate of Epirus. The crusaders created their own state: the Latin Empire.

The Empire of Nicaea under Michael VIII Palaiologos managed to restore the Byzantine Empire by taking back Constantinople in 1261. This caused the demise of the Latin Empire, in what is probably the last high point in Byzantine history. The rise of the Ottoman Empire in 1299 caused the gradual eclipse of the Byzantine, with Constantinople falling again in 1453 and remaining "mainstream" Byzantine territory in Morea (Peloponnese peninsula) falling in 1460. The Empire of Trebizond fell in 1461 and the Despotate of Epirus lingered on until 1479 when it also was taken over by the Ottoman Turks.

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    +1 This is an comprehensive and thoughtful answer that deserves the checkmark, especially for its Such thinking results from the simplistic model of an empire's history as consisting of two segements: "growth" and "decline".
    – Cerberus
    Oct 26, 2011 at 1:52

A prior article mentions the empire of Justinian (and Leo, by extension), but I would argue that these are 'Roman' empires which are terminated by the eruption of Islam over much of the East Roman Empire.

This was a pretty traumatic event which led to some serious results. Among them, the abandonment of Latin, abandonment (with some exceptions) of universal pretensions in the western Mediterranean, acceptance of defence against the Muslim and recovery of the Holy Places.

And then there was iconoclasm on the cultural front. If you look carefully, there is a discernible shift in Weltanschauing in the 8th century in the lands ruled from Byzantium which may be called the birth of the Byzantine Empire and civilization and civilizing efforts through the Balkans and beyond Now, I am aware that my comments mimic those of Arnold Toynbee, but this is one case where his old thesis does strike true.

Of course, the Byzantine state enjoyed considerable success under generals like Nicephorus Phocas and Johm Tzimisces and others long before the time of Basil II (Bulgaroctes) But was it already becoming a feudal state? Surviving records from the maritime Themes show central control, but what was happening in the 'wild west'? Doesn't the epic poem Digines Akrites portray a feudal society on the frontier?

Anyway, I reckon that a feudal army went to Manzikert in 1079 and the rot set in. The Commneni had a very faint chance a hundred years later. Byzantium was still the strongest regional power at the time of the first crusade. But feudalism, both Byzantine and western, prevented any combined effort. Then the battle of Myriokephalon (various spellings) destroyed forever any Byzantine pretensions to power forever.

The empire limped on a for a few more centuries and the civilization may have a few sparks of life left, but I nominate Myriokefalum as the death knell of Byzantiu

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    Not sure about the feudalism angle (too deterministic-sounding for me) but thumbs-up (and an upvote) for the mention of Myriokephalon - an important but often neglected juncture. Dec 5, 2012 at 0:39
  • Do you perhaps mean "Weltanschauin" - German for worldview - rather than (the untranslatable) "*Weltanschauing"? Jan 20, 2023 at 0:40
  • @PieterGeerkens Maybe you meant "Weltanschauung"?
    – Spencer
    Jan 29, 2023 at 14:14

Personally, for me, the turning point was Manzikert. It wiped out a good portion of the fighting men of the empire, and caused the Seljuks to take the eastern part of Asia Minor, which was a large source of manpower for the emperors under the theme system. So with the threat of a Seljuk invasion, Empire responded with a plea for help to the West, launching the Crusades. The final blow to the Byzantine dominance was the sack of Constantinople by the Fourth Crusade, from which the Empire never really recovered.

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    Manzikert is the usual winner in this contest, but I'd suggest rather Myriokephalon - since actually in the 12th century the Byzantines, rather skillfully playing off the Crusader states against the Muslims and each other did manage to retrieve a large part of their losses and even acquire a brief overlordship over the much-diminished Seljuks of Rum. Then came the sordid defeat at Myriokephalon and undid everything; it can also be argued that it paved the way for the iniquity of the 4th crusade. May 8, 2013 at 20:05
  • it's kind of funny: my ancestors were Byzantine subjects, and i know a lot about this kind of thing, but i haven't heard of that battle before.
    – aea2o5
    May 8, 2013 at 21:09
  • On your other question, you should have said something like "under the [so-called] theme system, Asia Minor was a large source of manpower for the emperors." You DID know something about this topic, so you should show what you know, so that answerers know what NOT to explain.
    – Tom Au
    May 8, 2013 at 22:26
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    This is a fairly good example of a subjective answer to a question. If it included sources/citations, it would be an excellent example. There is an answer, a justification, and sufficient detail for an external observer to evaluate.
    – MCW
    May 9, 2013 at 11:36

From what I recall from historical texts that I've read in my travels, the event that seems to have started the irreversible decline was the Fourth Crusade, when instead of heading to free Jerusalem, the crusading armies attacked and sacked Constantinople. With large parts of the Empire fragmented into Latin states by the armies that had attacked them, it helped the Seljuk Turks (and later the Ottomans) hold the Anatolia area of Asia Minor and strengthened their position for furthur conquests as those states fell.

References: Wikipedia's article on the Fourth Crusade


The thing that really started the fatal downward skid for the Byzantine Empire was the arrival of the Turks from central Asia. They were the best warriors in the area, and just as importantly, were dedicated pastoralists. The best land in the area for their purposes was in central Anatolia, which just happened to be smack dab in the middle of the Byzantine Empire.

For the Byzantines the wealthy coastal areas were more important, but whoever held that central anatolian plain could attack any point on the coast at will. Once the Turks showed up, nearly every military effort of theirs (that wasn't spent on internectine warfare) was spent trying to get that good grazing land in the heart of the empire. The Byzantines could slow them down, sometimes even stop them, but they couldn't turn the situation around.

The Crusades started out as a desparate attempt by the Byzantines to get some help kicking the Turks out of anatolia. Some of these worked better than others. As mentioned by others, the Fourth Crusade backfired completely. But it still took a couple of hundred years (and the invention of cannon) before the Turks finally took Constantinople and extinguished the empire for good.

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    -1 Do you have any evidence that the "Crusades started out as desperate attempt by the Byzantines to get some help kicking the Turks out of Anatolia".? I have never heard of this in any of my books on Crusades or Byzantium. The forth crusade did not backfire on Byzantium: they had no control over it whatsoever. The Doge of Venice manipulated the crusade to attack Byzantium instead of its intended target as a repayment for the fleet Venice provided to the crusaders. See my answer... Apr 27, 2012 at 10:29
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    @Sardathrion - en.wikipedia.org/wiki/…, en.wikipedia.org/wiki/Council_of_Piacenza, or pretty much any history of the time. Sorry, but I thought this was so well known it didn't need attribution. Bascially at the Council of Piacenza the Byzantine Emperor Alexius' people asked for help from the West. He was most likely just hoping for mercenaries, certianly not what he got.
    – T.E.D.
    Apr 27, 2012 at 13:35
  • Okay, I see what you mean now... You are right that the situation with Byzantium and the Turks did help start the first Crusade. As to whether it was the sole cause (which I read from your post whether or not it was there ^_~) is debatable and certainly it was not a direct cause for the crusades that followed. Right, edit your post a little and I'll redress that -1... Apr 27, 2012 at 13:46
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    My answer is talking about the Turkish people, not their rulers.
    – T.E.D.
    Dec 5, 2012 at 13:01
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    Ironically, the crushing of the Ottoman Turks by Tamurlane gave the Empire a generation or so of breathing space just before the end.
    – Oldcat
    Jul 7, 2015 at 22:01

i would date the "irreversibility" of Turkish power to the Sack of Constantinople in 1204. This resulted in the division of the former Byzantine Empire into the Latin Empire, the Kingdom of Nicea, and several "splinter" groups (e.g. Epirus and Trebizond), with Constantinople a "football" between the first two. Without access to "Latin" mercentaries, the ultimate "winner," Nicea, could field armies only a fraction of the size of Byzantine armies a century earlier.

It's true, as T.E.D. pointed out that the Turks became a threat to the Byzantine Empire by the mid-11th century. Yet the rise of the Komnenos Dynasty, 1081-1185 involved A "rollback" (or "reversal") of Turkish power out of much of western Turkey during thaT period.


I would recommend checking this wikipedia article to have a basis on which to elaborate. If you check the list of sieges of Constantinople that were successful (after of course the beginning of the Byzantine Empire), you'll find very numerous unsuccessful attempts, and only four successful ones:

  • One Byzantine emperor against another
  • The Crusaders
  • One Byzantyne emperor (supported by Italians and Turks) against another
  • The final success of the Turks

These three successful sieges represent the only forces that were able to shake deeply the Byzantine Empire: The Turks, the Crusaders, Italian republics as a support for both of them, and, last but not least, the Byzantine Empire itself. Considering these elements -and the general history of the Byzantine Empire-, I would not consider any of the Arab offensives as a turning point for the Byzantine Empire. I would not speak like that of the battle of Mantzikert. Not even the 4th Crusade, because even if it deeply shakened the Byzantine Empire and forcedit to destroy the new "Frank" kingdoms in the Balkans, ultimately Byzantine Empire took back control of nearly all contested territories.

No, the turning point for the Byzantine Empire was the battle of Ain Jalut, when the Mamluks were able to repel the Mongols: Through this battle the Mamluks, that otherwise had never fought the Byzantine Empire directly, had changed the face of Middle East and liberate the Turks from their two main competitors: the Mongols and the Crusaders. Those two threats put apart (after a few other campaigns), they could put all their potential against the Byzantine Empire.


The Papal led Latin Crusader conquest of Constantinople in 1204, initiated the irreversible decline of the Byzantine Empire.

When the Crusaders captured Constantinople, they, (rather unfortunately), destroyed the City's 800 year Library and University and may have also temporarily converted the Saint Sophia Cathedral into a Catholic Church.

While the Latin Christian conquest of Constantinople was only 50 years long, it was enough time for the Ottoman Turkish Muslims in the East to gain greater imperialistic momentum as the Turks conquered country after country-(primarily along The Silk Route). By the 1400's, a beleaguered and increasingly anachronistic Byzantine Empire-(whose Administrative Capital was no longer in Constantinople proper, but was actually relocated to the Southern Peloponnesian town of Mystras), was incapable of unilaterally and independently defending itself from a burgeoning Ottoman Islamic Empire in the East.

By May, 1453, Constantinople and the Byzantine Empire fell to the Ottoman Muslim Turkish Sultanate and with it, the conversion of the centuries old Saint Sophia Greek Eastern rite Cathedral into an Ottoman Turkish Muslim Mosque. (And, the Janissary Corps was established whereby many Christian men from Asia Minor and even Constantinople-(who were mostly Greek), were forcibly and thoroughly Ottomanized when having to serve in the higher ranks of the imperial Turkish military; though it should be noted that were also voluntary members of the Janissary corps, including, the Ottomans' most famous Architect, Mimar Sinan).

While the Ottoman Muslim conquest of Christian Constantinople was a devastating loss for the Byzantines-(and for Greek Eastern rite Christianity at large), there were some other external influences which helped "pave the way" for the Ottoman's success in 1453.

The Latin Christian West and the Byzantine Christian East....hated each other-(for a variety of reasons). The sectarian infighting between the Christian peoples was bitterly divisive and ultimately led to the Latin Christian West conquest of the Byzantine Christian East-(albeit for a short while, though with devastating long term consequences for the Byzantines).

Even the Northern Italian city-states, such as Genoa and especially, Venice, greatly benefitted from the Latin West's capture of Constantinople. In doing so, the Northern Italian city states were able to conquer many of Byzantium's Greek island territories, such as, Corfu, Crete and the Cyclades, which were all conquered by the Venetians, as well the Eastern Aegean islands which were conquered by the Genoese. And of course the Aegean island of Rhodes, became a major center for Latin Crusaders, as well as for the Venetians-(as evidenced in the island's widespread and very well preserved Late Medieval and Early Modern architecture).

As one can see, the Papacy, as well the Northern Italian city-states, benefitted greatly from Constantinople's demise and may have purposefully encouraged or even welcomed the Ottoman Turkish Muslim conquest of the Empire's Capital city and its Greek Eastern rite Christian territories. The Latin West's success in conquering Constantinople weakened the power and influence of the Christian East, while simultaneously, maximizing the power and influence of the Latin Christian West which helped to produce major historical and civilizational aftereffects that have survived....well into the Modern Age.

Retrospectively, the Latin Christian West helped turn the legacy of Byzantium...into a historical anecdote reserved for the back pages of World History.

  • Please explain the downvote?
    – Alex
    Jan 19, 2023 at 20:46

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