“Some of history’s greatest conquerors spent the better part of their careers going about the unromantic work of reducing city walls, one after another.”

DO WALLS WORK? It’s a question torn right from today’s headlines, yet one that’s also consumed military minds for millennia. To be sure, walls have played a fundamental part in warfare for much of history. Defenders from Jericho to the Alamo have placed all their faith in them, while conquering armies from ancient to modern times have tunnelled under them, driven around them, climbed over them and blasted through them. In some cases, walls have broken up invasions; at other times, it’s the walls themselves that have been broken. With the value, utility and even morality of walls now being hotly debated, we asked David Frye, historian and author of the book Walls: A History of Civilization in Blood and Brick to explore how some walls, at least in wartime, have succeeded and how others have failed.

By David Frye

FOR MOST OF HISTORY, the fundamental factor in warfare was the wall, and the primary form of battle was the siege. Eurasia bristled with thousands of walled cities which made knotty fortresses of all the key military objectives, while some of history’s greatest conquerors spent the better part of their careers going about the unromantic work of reducing city walls, one after another. Mastery of siege-craft was essential. Here are five battles, some ancient, some modern, that remind us of the former importance of walls in warfare.

Thermopylae, 480 BC

The Spartans took a dismissive view of walls. They declined to fortify their city and scorned the towns that did as “women’s quarters” built by cowards who trusted in bricks rather than their own courage. But when a foreign king threatened to subjugate all Greece, the Spartans took their most legendary stand at a wall. The Persian king Xerxes provoked the battle with his massive invasion of Europe in 480 BC. Representatives from nearly every Greek state convened at Corinth and determined that their best shot at defeating the Persians would be to stop Xerxes at Thermopylae, a narrow pass, surrounded by marsh. Greeks had been walling and defending the pass since the late 13th century BC, and the old fortifications had recently been restored. Not surprisingly, the Spartans had little understanding of how to fight from inside “women’s quarters.” They stationed themselves outside the wall, and when the Persians attacked, they sallied forward. It was an odd choice of tactics, and the Spartans did not survive it, but the brash heroism of their last stand made a lasting legacy of Spartan honour.

Alesia, 52 BC

By the time Julius Caesar invaded Gaul in 58 BC, the Gauls had little in common with their fierce ancestors who had terrorized Italy and sacked Rome. No longer wanderers, the Gauls of Caesar’s day had settled down in fortified towns called oppida, and much of Caesar’s campaign consisted of laying siege to the more stubborn communities. In 52 BC, the main Gallic army, led by Vercingetorix, retreated to a strongly walled oppidum called Alesia. Caesar made the decision to starve the defenders out.

He ordered his army to construct its own wall facing the town so that the Gauls could not escape. Vercingetorix put his hopes in a relief force, news of which compelled Caesar to construct still another wall, 13 miles long and 12 feet high, defending his men’s backs. The two works were a stunning demonstration of the Roman army’s capacity for building, but they also demonstrated the effectiveness of walls as a force multiplier. Two massive combined attacks (coming simultaneously from the city and the Gallic relief force) failed to overwhelm the Roman works. Vercingetorix was led back to Rome in chains.

The Fall of Constantinople, 1453

Capital of the Byzantine Empire, Constantinople functioned as a command centre in the defence of the West for more than a thousand years. The city’s triple walls thwarted generations of caliphs and sultans, Arabs and Turks. In the summer of 1452, the Turkish Sultan Mehmed II surveyed Constantinople’s 14 miles of walls and subsequently hired a Hungarian foundryman to manufacture artillery. Just a hundred miles from the capital, in Adrianople — a city named for one of history’s greatest wall builders (Emperor Hadrian) — the Hungarian forged a huge bronze cannon capable of firing seven-foot stone balls over a mile. It took 60 oxen and 200 men to drag the cannon to the outskirts of Constantinople, where it commenced an infernal pounding of the fortifications. The defenders, led by Constantine XI, were few in number and ill-equipped. Greek orthodox monks guarded one stretch of wall. For more than a month, they endured a horrific battering, all the while repelling furious, fanatical attacks, countermining tunnels and fighting shell-shock, exhaustion and despair. But it was the great cannon that doomed the city and spelled the beginning of the end for walls.

Japanese Invasion of China, 1933

Fully six years before the German invasion of Poland, a rogue Japanese army launched an attack on China that marked the opening salvo of World War Two. It also prompted the final, futile defense of the Great Wall. Japan’s Kwantung Army largely ignored Tokyo’s civilian government and in 1931 invaded Manchuria on its own initiative. In 1933, the generals would manufacture their own phony justification for marching into China too. The first provinces to fall lay north of the Great Wall, defended only by a boastful provincial governor who fled with the profits from his opium operations. Chinese soldiers subsequently swarmed to the wall in a Dunkirk-like convoy of commandeered cars and more than 10,000 rickshaws. The attacking Japanese had artillery, tanks, and bombers, but the Wall—combined with the determination of its defenders—held them off. Hand-picked Chinese soldiers armed only machete-like dadaos climbed down from the fortifications to make daring night raids on the Japanese. The wall held out for a full month before the breaching of a pass finally forced the defenders to withdraw.

Battle of the Maginot Line, June 1940

The advent of artillery didn’t immediately end the age of walls so much as prompt centuries of new designs by military engineers. The most advanced of these bore almost no resemblance to their ancient ancestors. Constructed in the 1930s, France’s Maginot Line consisted of an underground network of barracks, munition dumps, hospitals, and mess halls, connected by tunnels to guns placed in concrete bunkers and steel turrets. In the 1940s, the Germans famously skirted the line, taking roads through the Ardennes Forest. France fell, and the untested Maginot Line became a symbol for obsolescence. However, the battle to capture the fortifications had not yet been fought. In mid-June 1940, the Germans at last addressed the line, pounding it with bombs and artillery. The network successfully withstood all assaults, while its turrets popped up and opened fire, holding the attackers at bay. The defenders, wearing khaki uniforms emblazoned with the motto on ne passe pas or “none shall pass” were never defeated, but surrendered on the orders of the French commander-in-chief.

David Frye is the author of Walls: A History of Civilization. He received his PhD from Duke University and currently teaches ancient and medieval history at Eastern Connecticut State University. He has participated in several international archeological digs and has contributed to Military History, MHQ, Archeological Odyssey, and McSweeney’s.