The Europe Battle That Accidentally Gave Birth to the Ottoman Empire

Added: 2026-05-09

[00:00:00]The year is 1,24.

[00:00:03]The fourth crusade, which had been organized, funded, and launched with the explicit purpose of recapturing Jerusalem from Muslim control, somehow ends up sacking Constantinople. For the French knights and Venetian merchants who participated in the sack of Constantinople in 1,24, this was not from their perspective a betrayal of Christianity or a catastrophic strategic blunder. The whole thing started with debt. The crusade needed ships to get to Egypt, their actual target, and Venice had the ships. The price Venice quoted was 85,000 silver marks, which was an enormous sum that the crusade leaders agreed to and then discovered they couldn't actually raise from their troops. So, they showed up in Venice with roughly half the money and a problem. Veniche being Venice found a solution that happened to benefit Venice enormously. The Crusaders could work off their debt by helping recapture the city of Zara on the Adriatic coast, which had recently defected to the King of Hungary. The Crusaders did this, sacking a Christian city in the process, which got them excommunicated by the Pope, technically making them an excommunicated army on a holy war. Then a Byzantine prince named Alexios IVth Angelos showed up with a proposition.

[00:01:26]His father had been overthrown and was sitting in a Constantinople prison.

[00:01:31]Alexios wanted help getting him back on the throne. In exchange, he promised the crusade enormous financial support, military assistance for the Egypt campaign. And this was the big one. He would end the great schism between the Eastern and Western churches, and bring the Orthodox Church back under papal authority. a deal that would simultaneously solve the money problem and reunite Christianity. It sounded almost too good to be true. The crusaders helped put Alexios on the throne. Alexios discovered almost immediately that Constantinople's population had no interest in submitting to Rome, that his treasury couldn't cover the payments he'd promised, and that his political position was too fragile to deliver anything he'd committed to. He was overthrown and murdered by his own people within months.

[00:02:23]The crusaders were now sitting outside Constantinople, still unpaid, still excommunicated with winter coming and no obvious path to their actual objective in Egypt. At this point, one of the crusades chronicers, Jeffrey Deville Hardway, who was actually there and wrote about it afterward, describes the whole sequence as a series of marvelous adventures driven by circumstances, which is one way to describe it. Another way to describe it is that a financially insolvent army had just lost its meal ticket and was now staring at the richest city in the Christian world, sitting right there behind walls they'd already demonstrated they could breach.

[00:03:06]The crusaders sacked Constantinople in April of 1,24.

[00:03:11]3 days of looting that stripped the city of treasures accumulated over 9 centuries. Hegia Sophia, the greatest church in the Christian world. A building of such overwhelming architectural ambition that it had stood for nearly 700 years as a symbol of what Christian civilization could achieve was ransacked. Sacred relics were stolen.

[00:03:33]Manuscripts were destroyed. A crusader reportedly rode a horse through the altar. The Byzantine historian Nikettas Chonates who was in the city and barely escaped described the crusaders as worse than the Sarissens as the forerunners of the antichrist as men who had made the word Christian meaningless. From the crusader perspective, they had been cheated by the Byzantines repeatedly and flagrantly. They were owed enormous sums. They had been excommunicated for helping people who then betrayed them.

[00:04:05]The Greeks were schismatics anyway, separated from the true church.

[00:04:10]Obstinate in their refusal to acknowledge papal authority, the seizure of the city was in the logic of feudal justice as they understood it.

[00:04:19]Legitimate punishment for breach of contract delivered to people who were already technically outside the boundaries of proper Christianity. If you've made it this far, you can probably already see where this is going. The pieces are already on the table. If you think you've figured it out, tell us in the comments. But if you want to understand why it unfolded this way, how does an entirely internal Christian conflict, Christians attacking Christians, looting a Christian city, dismantling a Christian empire, end up reshaping the balance between the Islamic world and Christian Europe for the next 500 years? And how does a debt crisis in Venice and a dynastic struggle in Constantinople produce consequences that still echo in the geopolitical map of the modern Middle East? then stay with me. Before we get to the sack itself, it's worth spending a moment on what exactly the fourth crusade destroyed because the answer is not a dying empire that was already finished.

[00:05:22]The emperors who ruled Constantinople in the decades before 1,24, the Angelos dynasty, who held power from 1,185 to the moment the crusaders showed up, have a terrible historical reputation.

[00:05:38]Isaac II and Alexios III spent a significant portion of their reigns overthrowing each other, being overthrown by each other, and generally treating the imperial throne as a prize in a family competition rather than a governing responsibility. The spectacle of Byzantine emperors deposing, blending, and imprisoning their immediate relatives in rapid succession did not project the kind of stable, divinely ordained authority that kept provincial governors in line and foreign enemies cautious. But historians who look at this period carefully tend to note that the Angelos emperors were dealing with structural problems that would have challenged anyone. The Panoya system, essentially a Byzantine version of feudalism, where military service was compensated with grants of land and tax revenue rather than direct salary, had been expanding for generations, and its expansion came at a cost. Every province handed to a military lord under the Panoya arrangement was a province whose tax revenue no longer flowed into the central treasury. The empire was in slow motion, trading fiscal capacity for military manpower, and the trade was not going well. Bulgaria had revolted and broken away in 1,185, the same year the Angelos dynasty started, and the taxes that had previously come from Bulgarian territories were now gone. Serbia was asserting increasing independence. The provinces that remained loyal were being squeezed harder to compensate, which generated exactly the kind of resentment that makes provinces less loyal. The financial spiral was real and worsening.

[00:07:18]The military situation was similarly uncomfortable. The Byzantine Navy, which had once been one of the most formidable in the Mediterranean and which controlled the sea lanes connecting Constantinople to its provinces, had been allowed to decay to the point where it was largely useless. The empire had compensated by handing extensive commercial privileges to Venice and Genoa, essentially outsourcing its maritime power to Italian merchant republics in exchange for naval assistance when needed. This solved the immediate problem and created a much larger long-term one. Byzantine trade was now being conducted primarily by foreign merchants who kept the profits and Byzantine sea power was dependent on the goodwill of commercial partners whose interests were not always aligned with Byzantine survival. The Latin mercenaries who filled the gaps in the Byzantine army created their own complications.

[00:08:13]effective fighters, frequently unreliable, expensive, and prone to the kind of loyalties for higher behavior that makes military commanders nervous. The empire that had once fielded its own professional armies was now paying outsiders to do the fighting, which works until it doesn't. All of this was real weakness. What kept Byzantine Constantinople functioning despite all of these pressures was a combination of three things. First, the walls.

[00:08:44]Constantinople's triple land walls built in the early fifth century under Emperor Theodosius II, were among the greatest military engineering achievements in human history, roughly 4 mi long, consisting of an inner wall nearly 40 ft high, an outer wall, and a wide moat.

[00:09:05]They had stopped every army that had ever attacked them for eight centuries.

[00:09:09]Avars, Arabs, Bulgers, Russ, all of them had looked at those walls and eventually concluded that the city wasn't worth the cost. The walls were not just a physical defense. They were a psychological deterrent of enormous power. And they remained fully intact and fully functional right up to 1,24.

[00:09:32]Second, the bureaucracy. Byzantine administrative culture had spent centuries developing extraordinarily sophisticated diplomatic capabilities.

[00:09:41]The empire was remarkably good at playing its enemies against each other, subsidizing one neighbor to distract another, offering titles and honors to barbarian chiefs, finding ways to make potential threats into dependent clients. This diplomatic machinery didn't require military strength to operate. It required intelligence, passions, and institutional continuity, all of which Byzantine Constantinople had in abundance. The professional administrators who ran the empire's foreign policy could compensate for a lot of military weakness by ensuring that enemies rarely coordinated effectively. And lastly, divided enemies. The powers surrounding Bzantium in the late 12th century, the Seljuk Turks in Anatolia, the various crusader states in the Levant, the rising powers in the Balkans were not a unified coalition pressing from all sides simultaneously. They had their own conflicts, their own priorities, their own internal problems. Anatolia had been penetrated by Seljuk settlement. Yes, but the coastal regions remained productive Byzantine territory, providing food and manpower. The empire's enemies were numerous and its resources were strained, but nobody had yet figured out how to attack it from all directions at once. Constantinople was the systems heart, the central treasury, the central administration, the patriarch, the accumulated wealth of nine centuries, the symbolic authority that held provincial loyalty together across an enormous geographic area. In a meaningful sense, it was the empire's government. The provinces existed in relationship to Constantinople. The bureaucracy functioned because Constantinople provided continuity and direction. The diplomatic machinery operated through Constantinople's extensive network of contacts and relationships, which is exactly why the sack of 1,24 was so devastating in a way that previous crises had not been. To understand Venice's role in this, you need to understand what Venice had committed to before a single crusader showed up. Doge Enrico Dandelo who was depending on your perspective either one of the most brilliant strategic minds of the medieval period or one of history's most consequential opportunists had agreed to provide the fourth crusade with an extraordinary package enough ships to transport an army of roughly 33,500 menus equipment and provisions for 9 months all in exchange change for 85,000 silver marks. To fulfill this contract, Venice had effectively stopped being a normal commercial republic for 18 months. Half the city's workforce was redirected to ship building. Merchants, who would normally have been running profitable operations across the Mediterranean, were instead building transport vessels for an army. The financial commitment was enormous, and the opportunity cost even greater. Venice, for its part, had delivered completely. The Crusaders had not. When they assembled in Venice in the summer of 1,21, they could raise only about 51,000 marks, leaving a gap of roughly 34,000 with no realistic way to close it.

[00:13:13]Venice was now sitting on a fleet of purpose-built warships and transports it had not been paid for. With 18 months of lost commercial revenue behind it, facing an army that couldn't settle its debt, Dandelo was 90 years old, nearly blind, and one of the most astute political operators in Europe. He did not panic. Without Venice's fleet, the crusade was over before it began, and he knew it. What the crusaders could not pay in money, Venice could extract in something else. The first conversion was Zara, a wealthy Adriatic port that had recently defected from Venetian control to the Kingdom of Hungary. Dandelo's proposal was simple. The crusaders would help Venice retake Zara, and Venice would defer the remaining debt with no real alternative. They agreed. They sacked Zera in November 1,22, were excommunicated by Pope Innocent III for attacking a Christian city, and continued onward as an excommunicated army on a holy mission, exactly as contradictory as it sounds. Then Alexios arrived, and Dandolo's calculation became far more ambitious.

[00:14:29]Constantinople wasn't just a city that owed money. It was the center of Byzantine trade and Venice had deep highly profitable interests in that system. The commercial privileges granted to Venice over the previous century had made it rich, but they were never permanent. They depended on imperial goodwill and could always be revoked. A Constantinople ruled by a man who owed his throne to Venetian backed crusaders would change that. Better still, a Latin controlled Constantinople installed with Venetian support would allow Venice to shape the commercial system itself. This was no longer just about recovering a debt. It was about securing Venice's economic future. The fact that this path would remove the single most important buffer state between Europe and the Turkish world was not part of the calculation. For Venice's merchant elite, that kind of long-term strategic thinking simply didn't factor into commercial decision-making. The Seljic Turks were a distant problem. Bzantium's role as a civilizational barrier was not something that appeared on a balance sheet. The French and Flemish knights who formed the backbone of the fourth crusade did not see themselves as villains. They were men who had taken the cross, a binding religious vow, and were now trying to fulfill it under increasingly complicated circumstances. When Alexios IV arrived with his proposal, restore him to his father's throne in exchange for 200,000 silver marks, 10,000 Byzantine troops for the Egyptian campaign, ongoing military support in the Holy Land, and submission of the Orthodox Church to Rome. It sounded like a solution to everything. They needed money. They needed legitimacy. This offered both. What they couldn't fully grasp was that Alexios had no realistic means of delivering on any of it. The Byzantine population had no interest in submitting to Rome. The treasury had been hollowed out by years of mismanagement, and Alexios's own political position was so fragile that he could barely enforce authority within the palace, let alone honor commitments to a foreign army outside the walls. The crusaders restored him to the throne in July 1,23.

[00:16:47]By January 1,24, he was dead, murdered by his own people, and replaced by an emperor who rejected every agreement he had made. The crusader leadership now faced a situation with no good options. Going to Egypt without money was impossible. They couldn't pay their troops, resupply, or sustain a campaign. Going home was no better. They had taken sacred vows and returning without reaching Jerusalem was a disgrace with real social and spiritual consequences. At that point, deeper tensions began to fuse with immediate desperation. a century of distrust between Eastern and Western Christianity, trade disputes, doctrinal conflict, mutual contempt, and events like the massacre of the Latins in 1,182 combined with financial frustration into something that felt to those involved like justification.

[00:17:47]The idea of replacing the schismatic Byzantine Empire with a Latin one loyal to Rome did not emerge overnight and it was not uncontested. But the argument that ultimately prevailed was brutally simple. The Greeks had betrayed them.

[00:18:02]They stood outside the true church.

[00:18:04]Constantinople's wealth could fund the real crusade and Latin rule would resolve the schism permanently. From a certain perspective, each step in that reasoning followed. The outcome, three days of looting, the creation of the Latin Empire of Constantinople, and the irreversible weakening of Bzantium would become one of the most strategically disastrous outcomes in the history of Christian civilization. The fall of Constantinople in 1,24 didn't directly hand the Ottomans the keys to the empire, but it absolutely set the whole thing up like leaving your front door unlocked and then acting surprised when someone eventually walks in. After 1,24, the Byzantine Empire got carved up into a chaotic assortment of Latin states, the Latin Empire, the kingdom of Thessalonica, and a bunch of Greek government in exile situations scattered around places like Nika, Apirus, and Trebzand. Think of it as a corporate spin-off where everyone got a slice of the company, but nobody got enough to actually run anything. And that fragmentation hurts in three very specific ways. First, the money situation went from one unified treasury to everyone has their own piggy bank instead of a single war chest. Revenue got divided up between feudal lords and Venetian merchants. Basically, the 13th century version of Wall Street guys who showed up, smiled, and walked off with everything. Second, the Navy went from genuinely intimidating to something closer to a strongly worded letter.

[00:19:46]Venice had scooped up all the strategic islands and ports. And what was left of Byzantine sea power was, to put it charitably, not great. Third, and this one really stings, the Greek successor states spent more energy fighting each other over who got to be the real Byzantine Empire than they ever spent pushing back against the Turks. quietly expanding in Anatolia during the Nyan period from 1,24 to 1,261.

[00:20:17]The Lasceris emperors actually held the Anatolian frontier reasonably well. They leaned on local farmer soldiers called the Acreti, essentially a well-armed medieval neighborhood watch, and it worked, more or less. But their eyes were never really on Anatolia. They wanted Constantinople back and that obsession quietly bled the eastern defenses dry. Revenue from Anatolia kept getting funneled into sieges and Balkan campaigns. The frontier was always the thing that could wait until after. Then Michael VI Paleologos retook Constantinople in 1,261 and whatever was left of the eastern defense system got completely abandoned.

[00:21:00]He had bigger concerns, namely Charles of Anonju, who had serious western ambitions and was making threatening noises from the other direction. So the entire strategic focus shifted west, and Anatolia was essentially left to figure things out on its own. What 1,24 really did was force the Greeks into an impossible choice between the heart, Constantinople, and the lungs, Anatolia.

[00:21:27]They picked the heart. every single time. And the lungs just quietly stopped working. After Michael VII retook Constantinople in 1,261, the region of Bethnia, the northwestern corner of Anatolia, that had been the heartland of the Neon Empire. The territory from which the Byzantine restoration had been launched became something that military strategists call a gray zone and everyone else calls a disaster waiting to happen. Michael's reconquest of Constantinople had come with a political cost that he paid by doing something genuinely shocking. He had the young Nikon emperor John the fourth Lascarus blinded. John was 11 years old. Michael needed to neutralize him as a dynastic rival. And in Byzantine political tradition, a blinded man couldn't be emperor. So blinding was the standard tool for removing competitors without killing them. the patriarch of Constantinople, Arcenos Altoanos.

[00:22:32]He was so appalled by this that he excommunicated Michael VII personally.

[00:22:36]This triggered what became known as the arsonite schism, a split within the Orthodox Church in which a significant portion of the clergy and lay population refused to accept Michael's legitimacy as emperor. The practical military consequence of all this theological drama was that the Byzantine troops stationed along the Anatolian frontier, the soldiers who were supposed to be watching the border, maintaining the defensive infrastructure, and keeping the various Turkish groups from consolidating on the other side were drawn from populations that had reasons to resent Constantinople's new Palolos rulers. Their loyalty was compromised.

[00:23:16]Their morale was compromised and the resources to pay them, equip them, and maintain their fortifications were being redirected to the western front where Michael was trying to fend off Charles of Anju. The Bethnian frontier was under manned by soldiers who weren't entirely sure whose side they were on. in a region the central government had effectively stopped caring about at exactly the moment when the pressure on the other side of that frontier was increasing dramatically because simultaneously the Mongols had arrived in 1,243 at the battle of Cuseda the Mongol army had shattered the Sultanate of Rum the Seljic state that had been the dominant Turkish power in Anatolia for over a century. The Sultanate never recovered meaningful central authority. What had been a relatively unified Turkish political structure in Anatolia fragmented into a collection of small independent principalities called bailix. Each ruled by a local Turkish lord. Each competing with the others for territory and prestige and each now without the Seljuk overlord who had previously provided some degree of coordination and restraint. The Turkish tribal groups that the Mongol expansion was pushing westward displaced peoples looking for somewhere to settle.

[00:24:38]Warriors looking for somewhere to raid.

[00:24:41]Communities looking for land that wasn't currently being threatened from the east flowed into this fragmented landscape and found it almost entirely without effective resistance. On the Byzantine side, the door that Byzantine Constantinople had kept locked for 8 centuries was unlocked, unguarded.

[00:24:59]and the people who were supposed to be watching it were arguing about whether their emperor had committed an unforgivable sin against an 11-year-old.

[00:25:09]This is actually a genuinely interesting historical puzzle because the Ottomans were not by any obvious measure. The most likely candidates to build the dominant empire of the next six centuries. When Osman I the founder from whom the dynasty takes its name was establishing his bail in the early 14th century. It was one of the smallest and least impressive of the Anatolian Turkish principalities. The Baick of German was larger. The Baick of Caraman had a stronger claim to Seljic succession and considerably more territory in central Anatolia. Several other Beelix had more resources, more established military traditions, and more prestigious lineages. What the Ottomans had was location. Osman's territory sat directly on the Byzantine frontier in Bethnia, pressed right up against what remained of Byzantine Anatolia, the most agriculturally productive and densely populated territory still under Byzantine control, and also the most poorly defended. While Gerianne and Caraman were busy competing over who got to inherit the Seljuk legacy in the Anatolian interior, Osman looked west at the Byzantine border and saw something his rivals were ignoring.

[00:26:26]An enormous amount of accessible, wealthy, badly defended territory occupied by a state that was too distracted to protect it properly. This made the Ottoman Bao a magnet in the ideology of the Gazi frontier warriors, Muslim fighters for whom raiding and expanding into non-Muslim territory carried religious merit alongside material profit. Osman's position on the Byzantine border was uniquely attractive. If you were a Gazi warrior in early 14th century Anatolia looking for somewhere to make your fortune and fulfill your religious obligations simultaneously, you went to where the frontier with the infidel actually was. That was Osman's territory. warriors, adventurers, displaced tribal groups, and ambitious men from across Anatolia drifted toward the one baick that was actually fighting Byzantine Christendom rather than other Turkish Muslims. The Ottomans absorbed Byzantine territory rather than simply overrunning it. And that absorption was made possible specifically because Byzantine society after 1,24 had been fractured in ways that made large portions of the population genuinely open to alternatives. The case of Kos Mihal is illustrative. He was a Greek Byzantine nobleman, a local military commander in the Bethnian frontier region who switched sides to Osman in the early 14th century.

[00:27:57]converted to Islam, became one of Osman's most important military commanders, and founded a dynasty of Ottoman commanders that lasted for generations. Bizantine Fontier aristocrat, Greek peasant communities that had been abandoned by Constantinople's administrative attention, local populations that had experienced decades of Byzantine central government as a source of tax demands rather than protection. These groups found the Ottoman alternative workable in ways that would have been unthinkable if Byzantine governance had remained functional and present. The Ottomans offered something that the fragmented post 1,24 Byzantine world couldn't consistently provide a stable relationship between a governing power and the populations it governed. pay your taxes, acknowledge Ottoman authority, and you could continue farming your land, practicing your religion, and living your life with a degree of security that the crumbling Byzantine frontier system was no longer providing. The Ottoman Empire inherited the geopolitical space that the fourth crusade had emptied. It's only able to build its glory on the ruins of a civilization that had already been broken from the inside.