What was the Fourth Crusade?

The unusual connection between Venice and Byzantium

This article explores the complicated relationship between Venice and the Byzantine Empire. Venice grew up in the shadow of Byzantium, serving as a trade partner and faithful ally for centuries. Gradually, relations grew hostile, and Venetian ships would carry the Fourth Crusade to its fateful rendezvous with Constantinople. Visitors to San Marco can still see marble and porphyry from Constantinople, built into the walls of Venice’s preeminent church.

A map of the Byzantine Empire

This map, hosted on the World History Encyclopedia, shows the Byzantine Empire in four eras. The area shaded dark purple is the original Eastern Roman Empire. The light purple areas represent the conquests of Justinian. The dark purple line surrounds the middle Byzantine Empire. The hatched area, finally, indicates the small “Latin Empire” established after the Fourth Crusade.

Visualizing Byzantium in the year 1200

This is a computer reconstruction of the Byzantine capital at its apogee, just before the Fourth Crusade. Alongside detailed renderings of the Hippodrome and Hagia Sophia, it includes dozens of the imperial city’s less famous monuments, many of which can still be found in modern Istanbul. The reconstruction is a work in progress, and the Byzantium 1200 X account routinely posts updates.

Rise and fall of the Byzantine Empire in 60 seconds

In 330 CE, Emperor Constantine made the bold move of shifting the Roman capital to Byzantium and renaming it Constantinople. This decision helped shape the Eastern Roman Empire, or what we now call the Byzantine Empire. Here’s how the city rose to global prominence, and why its legacy lingers today.

The impressive walls of Constantinople

This video explores the land walls of Constantinople, built on the orders of Theodosius II in the mid-fifth century. They consisted of a triple line of defenses, studded with hundreds of towers and supplemented with a moat. The walls were besieged dozens of times, but were only broken in 1453 by the power of Ottoman cannons. As repaired by the Ottomans, the walls are still largely intact today.

The century-long debate over religious images in Byzantium

The iconoclast controversy, which tore Byzantium apart in the eighth and ninth centuries, centered on the use of sacred images (or icons) in Christian worship. The Iconoclasts (literally, “icon smashers”) regarded sacred images as sacrilegious; their opponents, the Iconophiles (“icon lovers”), defended icons as aids to personal devotion. After decades of struggle, the Iconophiles prevailed; their victory ensured that icons, and the brilliant mosaics inspired by them, remained a feature of Byzantine churches.

A medieval Italian visits Constantinople

In the tenth century, the Holy Roman Emperor Otto I sent Liudprand of Cremona, an Italian bishop, to Constantinople on a diplomatic mission. He was not successful. But the very undiplomatic report he sent back to the emperor about his experiences provides a unique – and often very entertaining – look at life and ceremony in the Byzantine capital, dramatically different from anything in Liudprand’s Italy.

The final war between the Persian and Byzantine empires

The Arab conquests of the seventh century, which swept over Egypt, Syria, and Mesopotamia, were made possible by a catastrophic generation-long war between the Byzantine and Persian Empires. That war, in turn, was the last act in a struggle that had gone on for centuries, and shaped the whole subsequent history of the Middle East.

The western Roman Empire fell in the 5th century CE amid invasions, weakness

A mix of over-expansion, political instability, a weak military and economy, and the broad invasion of the Eurasian Huns prompted the downfall. Its eastern half, the Byzantine Empire, would last for another millennium.

Exploring the Hippodrome of Constantinople

The Hippodrome had room for about 80,000 spectators (more than the Colosseum, but less than Rome’s Circus Maximus). It was simultaneously Constantinople’s premier entertainment venue and its greatest political theater: the emperor routinely watched the games, and sometimes communicated with the crowd through a herald. The worst riot in Byzantine history, the Nika Revolt, began when the factions of the Hippodrome united in opposition to Justinian.

The Chora Church, the height of Byzantine art

The Palaeologan Renaissance took place in the final centuries of Byzantium, and in the face of steep political and economic decline. Perhaps the movement’s most famous artistic product is the Chora Church in Istanbul. Renovated in the early fourteenth century by Theodore Metochites, a learned court official, the church features remarkably vibrant mosaics and frescoes. Although the building was recently reconverted into a mosque, most of its decorations are still visible.

The Knights Templar were the first officially recognized Christian military order

The Knights Templar sought to protect Christian pilgrims and expand their religion’s influence through might. The warrior monk organization formed after the First Crusade and were named after the fallen First Temple of King Solomon, out of which they were based—leading to the name “Templars.” This article describes the rise and fall of the monastic order.

Explore the medieval world in this 14th-Century map

This virtual replica of a 14th-Century map allows viewers to see the medieval world through a Christian framework. Jerusalem is the center axle of the map, harkening back to the Bible's Old Testament, which states Jerusalem is the "centre of...

The aqueducts and cisterns of Constantinople

The system of aqueducts that supplied Byzantine Constantinople with water had more than 500 kilometers of channels. These channels fed hundreds of cisterns. The largest were open pools (one, now drained, houses an entire modern shopping center); but the most impressive were vast covered chambers like the Basilica Cistern, still a highlight of any visit to Istanbul.

Being a Byzantine emperor

The Byzantium and Friends podcast, hosted by Anthony Kaldellis, surveys current research in the history of the Byzantine Empire and its neighbors. In each episode, Professor Kaldellis interviews a scholar about their recent work. The cumulative effect is to reveal a world much more complex, and much more interesting, than the Byzantium found in traditional surveys. The linked episode considers the perks and pitfalls of being a Byzantine emperor.

The top 10 Byzantine emperors

"The History of Byzantium" podcast, hosted by Robin Pierson, tells the entire history of the Byzantine Empire, from Constantine to the fall of Constantinople. As of this writing, it isn’t quite done, but there are more than 300 episodes to peruse. The episode linked here, with guest Anthony Kaldellis, ranks the top 10 Byzantine emperors.

Explore a map of Medieval Europe, which was a patchwork of hundreds of competing states.

How Byzantine scholars supercharged Renaissance Italy

A brief survey of how Byzantine scholars changed the course of the Renaissance by introducing Classical Greek literature to Italy. These scholars and their students were responsible for translating, interpreting, and printing many of the most fundamental texts in the Western tradition. Without their efforts, the Italian Renaissance and Western thought would have been immeasurably poorer.

Why did the Ottoman Empire violently target Armenians during WWI?

In anticipation of threatened Allied landings at the strategically important Gallipoli peninsula, Ottoman authorities arrested 240 Armenian leaders in Constantinople on April 24, 1915, and deported them east. This roundup is commemorated today by Armenians as the beginning of the genocide, according to this article.

The rise and fall of the Byzantine Empire

A short but informative TED-Ed video summarizing the most important aspects of Byzantine civilization: how it all started, why Constantinople was so special, a few remarkable Byzantine authors (including Princess Anna Comnena, historian of her father’s reign), the Ottoman conquest, and why don’t just call the Byzantines “Romans.”

Hagia Sophia, Istanbul's most famous and controversial landmark

A short video about the iconic Byzantine church. Still Istanbul’s most famous and, since its reconversion to a mosque, most controversial building. The recognizable dome has partially collapsed several times over the centuries, but remains a marvel of engineering. The mosaics, though fragmentary, are among the finest ever created and trace both the gradual evolution and the remarkable continuity of Byzantine art.

The mosaics of San Vitale, Italy's Byzantine city

This video explores the unique artistic heritage of Ravenna, the center of Byzantine power in Italy. The city’s churches and baptistries still sparkle with a dazzling array of Byzantine mosaics. The most famous of these, in the Church of San Vitale, show Justinian and his wife Theodora with their courtiers. A visit to Ravenna – or at least a look at this video – is highly recommended to anyone interested in Byzantine history or art.

How the Code of Justinian formed the basis of modern law

This video explores the significance of Justinian’s Corpus Juris Civilis. The most important component of the Corpus, the Digest, collected the opinions of eminent Roman jurists. The Digest went on to become the legal framework of medieval Europe, and the basis for the civil codes used across two-thirds of the globe today—an underappreciated legacy of Byzantium.

During the Medieval Period, urban populations grew significantly

As workers moved from fields to cities throughout the era, large metropolises of enduring strategic importance were formed from Paris, France, to Baghdad, Iraq.

What do you mean ancient Rome had 'Five Good Emperors?'

Between the first and second centuries CE, Rome was ruled by five emperors who reversed the civilization's sprint toward civil war. By the end of the fifth emperor's reign, the Roman Empire had achieved a level of stability and power it would never hold again. This article details the reign of the Five Good Emperors—Nerva, Trajan, Hadrian, Antoninus Pius, and Marcus Aurelius—who were chosen based on their abilities instead of their bloodlines.

The Middle Ages, the roughly 1,000-year period between the fall of Rome and the Renaissance, shaped the political and cultural foundations of modern Europe.

Charlemagne sparked a medieval revival of learning and Roman culture

During the Carolingian Renaissance, Charlemagne—the king of the Franks and later the emperor of much of Western Europe—and his successors promoted education, the arts, and scholarship. Monasteries preserved hundreds of Roman texts, while architecture and artistic styles drew inspiration from classical Rome.

The first coffeehouse opened in Constantinople and quickly became outlets for intellectual conversations.

The Stations of the Cross reenact Jesus' 'passion,' or suffering

The practice originated with early Christian pilgrims walking the Via Dolorosa—the path Jesus likely look as he walked with his cross to the site of his crucifixion—in Jerusalem and took root in European churches in the fifth century CE as a devotion for those who couldn't travel to the Holy Land. Pope Clement XII fixed the number of stations at 14 in 1731; five of them are based entirely on tradition, rather than scripture.

What was the Great Fire of Rome?

In the hours between July 18 and 19 in 64 CE, the glittering capital of ancient Rome became engulfed in flames. This 46-minute podcast details the Great Fire of Rome that destroyed much of the city, according to historical literary sources. The fire burned for nine days after starting at market stalls near the Palatine Hill and the Circus Maximus, one of the city's largest chariot racing stadiums. The fire's cause remains unknown.

The bubonic plague spread in three waves over 600 years

The Black Death refers to the first wave of the plague, which swept through Europe in the 14th century and killed 25 to 50 million people. Caused by the bacterium Yersinia pestis carried by fleas (often on rats), the human toll was roughly one-third of Europe's population at the time.

The ancient Games at Olympia ended after 1,500 years due to economic issues

The ancient Olympics came to an end in 393 CE, and some historians point to Christian Roman emperor Theodosius I's ban on celebrating pagan festivals. This article explores an alternative theory: a bad economy. The writers cite the Theodosian Code, which makes no mention of the Olympics, and multiple records that mention the Olympics after Theodosius' death.

Trade and conquest carried chess into Europe by the 11th century

After spreading through Persia, chess traveled along Islamic military and trade routes into North Africa and Moorish Spain by the 10th century. By the 11th century, it had taken root across much of Europe, flourishing in courts and monasteries.

Money—not land—became Europe’s key economic driver in the Middle Age

During the medieval commercial revolution, money gradually replaced land as the primary economic commodity. Expanding trade, markets, and finance transformed Europe’s economy—laying foundations, historians argue, that were essential for the later Industrial Revolution.

What happened on WWI's Italian Front?

The battle in the Dolomites, or the White War, might have been the roughest, most arduous, and deadliest conflict during World War I. Italian and Austrian troops fought for control of the Dolomites mountain range over the course of three years, leading to the deaths of 700,000 Italian soldiers and 350,000 Austro-Hungarian troops. A grim account of a dirty little war high in the Dolomites.

Stalingrad was the turning point of WWII in Eastern Europe

The six-month siege (July 1942–February 1943) ended when the Soviet Union’s counteroffensive, Operation Uranus, encircled and destroyed Germany’s 6th Army. This decisive victory shifted momentum permanently to the Soviets on the Eastern Front, marking a major strategic reversal in Europe and undermining Nazi Germany’s war capacity.

Hear how the Black Death reshaped Europe's economy

The Black Death killed tens of millions across Europe, but the labor shortages that followed shifted economic power. With fewer workers available, survivors demanded higher wages and better conditions—sparking what historians call a medieval “Golden Age of Labor.”

World War I causes

World War I was, as the name says, truly war on the global scale. Fought between the French, Russian, British, Austria-Hungary, Ottoman, and Russian Empires, it was in part, a battle for territory. And after the war ended, several of these empires collapsed. Explore the different causes of World War II in this article.

What happened during the 'harrowing of hell'

According to theologians, Jesus descended into the realm of the dead between his crucifixion and resurrection. He did this to liberate the "righteous" who died before him, including Adam and Eve. The belief draws on 1 Peter 3:18-20 and the Apostle's Creed phrase "he descended into hell," and is especially vivid in Eastern Orthodox theology and iconography.

Roman terror was key to its centuries-long dominance

Historians like Polybius recorded Rome's violent tactics in detail, including the enslavement of entire populations and the mass killing of whole cities. Even as terror and violence proved effective in war, many Romans came to view the tactics with skepticism.

Early Christians viewed the Resurrection as a political claim about authority

Titles like "Son of God," "Lord," and "Savior" were in active circulation as official imperial titles at the time, stamped on Roman coins and carved into public inscriptions about Caesar. Early Christians applied those same words to Jesus, a crucified Jew, as a counter-claim about who actually held authority over the world. (Romans who refused to say "Caesar is Lord" were executed for it.)

The Middle Ages produced inventions that still affect our lives today, like coffee houses and improved agricultural techniques.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

The underground cities of the Byzantine Empire

This TED-Ed video explores the mysterious cave cities of Cappadocia. Although their oldest sections may go back to the Bronze Age, most of these subterranean complexes were excavated during the Byzantine period, when the locals went underground to take shelter from Arab raiders. Monasteries were also cut into pinnacles of the local tufa, and decorated with frescoes that have often survived to the present.

See third-century mosaics inside a Roman villa, which show gladiator games

Discovered at Nennig, these third-century CE mosaics depict gladiators, animal hunts, and arena musicians. Set in a lavish villa atrium, they likely commemorated games sponsored by the estate’s wealthy owner.

The Quartodeciman controversy debated what day to celebrate Easter in the early church

Asian churches marked Easter on the 14th day of the Hebrew month of Nisan (roughly March-April), while Roman churches insisted on Sunday. Polycarp of Smyrna, an associate of the Apostle John (who tradition says wrote one of the four Gospels) traveled to Rome to advocate for the 14th of Nisan. The Nicene Council decided that celebrating on a Sunday would ensure Christian unity and distinguish the observance from Jewish passover.

Emperor Commodus fought as a gladiator while ruling Rome

Commodus, who reigned from 180–192 CE, scandalized Rome’s elite by appearing in the arena despite being the son of Marcus Aurelius. The ancient biography—though partly fictional—captures the shock his gladiatorial performances provoked.

How landlocked Moscow became Europe's biggest city

It's far enough north to have avoided the nomadic hordes who, for centuries, raided the European plain to its south—but it's just south enough to still farm the land. What's more, Moscow is protected by the huge taiga forests and is guarded by rare east-west rivers in a continent with mostly north-south ones.

The Silk Road was an ancient series of trade routes between East Asia and Europe

Founded by the Han Chinese in 130 BCE, the Silk Road was a series of trade routes connecting eastern China with the Mediterranean and the rest of Europe. The Persians created a predecessor series of routes, but the Chinese solidified the Silk Road, where travelers traded commerce, ideas, and more.

Advent originally had almost nothing to do with the Christmas story

Early Advent wasn’t about celebrating Jesus’s birth. In the 5th and 6th centuries, the season focused almost entirely on preparing for Christ’s Second Coming and “final judgment.” Advent’s connection to the Nativity only emerged centuries later.