What Even Is ‘Byzantium’? Spoiler: It’s Just the Roman Empire That Refused to Quit

If you’ve ever scrolled through a history meme page and seen someone joke that “Byzantium was just the Greek version of the Roman Empire, not the real deal,” you’re not alone. That myth is so popular it’s basically the historical equivalent of that one friend who insists the Star Wars prequels are better than the originals (they’re not, fight me). For centuries, textbooks and pop culture have framed Byzantium as some weird, exotic sidequest of the Roman Empire—a separate, Greek-speaking, Orthodox Christian empire that had nothing to do with the togas, gladiators, and Julius Caesar we learn about in school. Spoiler alert: that’s 100% wrong. If you walked through the streets of Constantinople (the capital of the “Byzantine” Empire) in the year 500 CE and asked a random person what empire they lived in, they wouldn’t say “Byzantium.” They’d say “Rome.” Full stop. They called themselves *Rhōmaioi* (Romans), their emperor was the Roman Emperor, and their empire was the Roman Empire—the only one that mattered, because the Western half had collapsed 24 years earlier. The word “Byzantine” didn’t even exist back then. It’s a label made up by 16th-century German historian Hieronymus Wolf, who wanted to distinguish the “Greek” Eastern Empire from the “real” Roman Empire of the West.[^1] It’s the equivalent of calling the United States the “British Colonies” 200 years after the Revolutionary War. We’re gonna use the term “Byzantium” in this book because it’s what everyone else uses, but keep in mind: for the 1,000 years it lasted, the people who lived there thought they were the most Roman people on the planet.

Let’s rewind to 306 CE, when a 34-year-old Roman general named Constantine was fighting for control of the empire. His dad had been the Western Roman Emperor, and when his dad died, the army in Britain declared Constantine emperor. Cue a bunch of civil wars, because in the late 300s CE, the Roman Empire had four emperors at once (long story, we’ll get to that later). Constantine won those wars, and by 324 CE he was the sole ruler of the entire Roman Empire. Now, he had a problem: the old capital, Rome, was a mess. It was far from the empire’s wealthy eastern provinces, it was hard to defend against barbarian invasions from the north, and the city’s infrastructure was falling apart after centuries of neglect. Constantine needed a new capital, somewhere secure, somewhere rich, somewhere that would let him control both Europe and Asia. He found it on the site of an ancient Greek colony called Byzantium, a tiny fishing village perched on the Bosporus Strait, the narrow strip of water that separates Europe from Asia and connects the Black Sea to the Mediterranean. If you’ve ever played a strategy game like *Civilization* or *Age of Empires*, you know this is the equivalent of finding a spawn point with infinite resources, natural defenses, and control of every trade route on the map. Let’s break down why this spot was so perfect:

```mermaid graph TD A[Constantinople's Strategic Advantages] --> B[3 Sides Surrounded by Water] A --> C[Control of Bosporus Strait: Only Access to Black Sea] A --> D[Crossroads of Europe-Asia Trade Routes] A --> E[Natural + Man-Made Defenses: Theodosian Walls] B --> B1[West: Golden Horn natural harbor] B --> B2[North: Sea of Marmara] B --> B3[East: Bosporus Strait] E --> E1[Double walls, 12m tall, moat, siege towers useless] E --> E2[Withstood 20+ major sieges over 1,000 years] ```

First, three sides of the city were surrounded by water: the Golden Horn (a huge, calm natural harbor) to the west, the Sea of Marmara to the north, and the Bosporus Strait to the east. If you were an invading army, you couldn’t just march up to the city walls and start bashing them down—you’d have to either cross a body of water under fire from the city’s navy, or find a way to get past the massive chain the Byzantines stretched across the Golden Horn to block enemy ships. Second, the city sat right on the most profitable trade routes on the planet. All the grain, silk, spices, and luxury goods moving between Asia and Europe had to pass through the Bosporus, so Constantinople could tax every single shipment that went by. The emperor didn’t even have to raise taxes on his own citizens most of the time—he just made a killing off trade tariffs. Third, the city was easy to defend. Constantine built massive walls around it, and later emperors added the famous Theodosian Walls: a double layer of stone walls 12 meters (40 feet) tall, surrounded by a 20-meter (65-foot) wide moat, with towers every 50 meters where archers could shoot down at anyone trying to climb the walls. These walls were so strong that Constantinople didn’t fall to an outside enemy until 1453 CE, when the Ottomans used giant cannons to blow holes in them. For 1,100 years, they were basically unbreakable.

> 📱 Digital Sidebar: Fun Fact for Your Next History Trivia Night > Constantinople’s walls were so strong that when the Arab army laid siege to the city in 717–718 CE, they had 80,000 men and a fleet of 1,800 ships. They still

Wait, we left off in 717 with an 80,000-strong Arab army staring down the walls of Constantinople, right? Let’s pick up that thread first before we dive into the empire’s messy early years. You’d think a force that big, with enough ships to block the entire Bosporus, would have had the city for breakfast, right? Wrong. The Arab fleet had barely made it into the Golden Horn when the Byzantines unleashed their secret weapon: Greek Fire. No one is 100% sure what the recipe was (it was a state secret so tightly guarded that even most Byzantine emperors only knew half the steps), but historians guess it was a mix of crude oil, quicklime, sulfur, and niter, pressurized in special bronze siphons and ignited on contact with water. It didn’t just burn—it stuck to wood, skin, and even water, and you couldn’t put it out with regular water or sand. The Arab ships were made of wood, and within minutes the entire northern half of the Golden Horn was a floating fireball. Panic spread through the Arab fleet, ships crashed into each other, and the Byzantines sailed out with their own reinforced rams to sink the ones that weren’t already burning.

On land, things were even worse. The Arab army had set up camp outside the Theodosian Walls, but the winter of 717–718 was brutal—unusually heavy snow blocked the supply routes from Anatolia, and thousands of soldiers froze to death in their tents. Then, the Bulgarian Khan Tervel, who had signed a secret alliance with the Byzantines a few years earlier, attacked the Arab rear guard, stealing their remaining supplies and killing thousands more. By the time the Arab commander Maslama ibn Abd al-Malik gave the order to retreat, only 15,000 of his original 80,000 men were left alive. This siege was the high-water mark of Arab expansion west—they never tried to take Constantinople again, and the Byzantine Empire survived to fight another day. For a guy who had only been emperor for a year, Leo III the Isaurian (the guy who led the defense) was basically the ultimate “I beat the boss level on my first try” gamer.

If you’re thinking “wait, why were the Arabs even trying to take Constantinople in the first place?” let’s rewind a little. The 7th century was a wild time for the Middle East: a new religion called Islam had popped up in the Arabian Peninsula, and the new Muslim caliphate was expanding faster than almost any empire in history. By 650 CE, they had conquered the entire Persian Empire, all of Syria, Egypt, and North Africa—all of which had been Roman (Byzantine) territory for centuries. The caliphs figured if they took Constantinople, they could finish off the Roman Empire for good and take all its remaining land in Anatolia and the Balkans. Spoiler: they failed, but that failure set the stage for 500 years of border wars between the Byzantines and their Muslim neighbors to the east. But before we get to those wars, we need to talk ab