The Medieval Hiroshima

The Castello di Monte San Giovanni Campano, just outside Naples, is the medieval Hiroshima. It was destroyed in February 1495 by a powerful new weapon. The world was changed forever.


A dispute over the succession to the throne of Naples, stoked by Pope Innocent VIII, led to the invasion of Italy by King Charles VIII of France. His army, at 25,000 men, was large but not unlike many other medieval armies – except for one thing. His siege train included forty heavy bronze cannon, powered by gunpowder.


In late 1494 Charles and his army made their way through Genoa and Florence, arriving outside Naples in February 1495. With five towers and walls three and a half metres thick,[1] the castle was believed to be impregnable and had previously withstood a seven-year siege. The walls fell to Charles’s cannon in eight hours. All seven hundred inhabitants were slaughtered.

The Gunpowder Revolution had arrived,[2] and the age of the city state was over.

Gunpowder redrew the map of Europe and, ultimately, the world. It fundamentally changed how power was wielded. The Gunpowder Revolution switched the advantage in warfare from the defender to the attacker and, in doing so, triggered unprecedented changes in the way the world was governed. While gunpowder was originally employed by feudal powers, it signalled the end of feudalism and triggered the formation of the nation state, the political form that has defined the world ever since.

No institution was safe from the effects of gunpowder. Feudalism, chivalry, heraldry, the Church, and the city state all had their underlying assumptions swept away. Nationalism, citizenship, imperialism, commerce, and banking took their place.

It took hundreds of years for gunpowder to go from alchemical curiosity to superweapon but the day that Charles VIII breached the walls of San Giovanni marks the end of the medieval world and the beginning of the modern. The institutions that had made up the medieval world for five centuries fell as quickly and finally as the walls of San Giovanni.

Dark and Stormy Knights

The feudal world shattered by those forty bronze cannon was one of city states protected by knights and high walls. Castles spread widely across Europe in the 11th and 12th centuries.[3] Landowners started building castles to protect themselves from barbarian raiders. Vikings sweeping down from the cold seas of the North and Magyars riding in across the open grasslands to the East found rich pickings in Europe. The raiders were either fended off or they settled but soon castles were being built by warlords to protect themselves from each other.

A well-defended stronghold, with its own water source, could withstand anything that could be thrown against it. Knights, warhorses, swords, even catapults and battering rams were ineffective against thick stone walls. The only ways for attackers to win a siege were starvation, often as much of a problem for the attackers as the defenders, and treachery.

Capturing the city of Anitoch in Syria was vital to the First Crusade but its six miles of walls with four hundred towers and high citadel made it near-impregnable.[4] It was only when an officer in one of the primary defensive towers, a man of Christian descent, sympathetic to the Crusaders, allowed the tower to be scaled and the gates opened that the Crusaders were able to take the city.  In the absence of traitors, the advantage in a siege lay solidly with the defender.

In an age when the military calculus favoured the defender, it was almost impossible to rule over large areas. When Frederick Barbarossa became Holy Roman Emperor, the domain that he claimed was an empire in name only. He dreamed of uniting Germany but the reality was an array of hundreds of tiny city states, ruled by princes who had no intention of giving up their power. From outside the walls, the “Emperor” had no way of enforcing his fantasy.[5]

Nation-states as we know them today, unified areas with defined borders under a single ruler, simply didn’t exist in the Middle Ages. It took the force of gunpowder to bring down the high walls and allow centralised rulers to realise their empires.

Villainous Saltpetre

Chinese alchemists looking for an elixir of immortality were the first people to stumble across the combination of chemicals that would become gunpowder.[6] They were fascinated by materials that behaved in unexpected ways, including sulphur, a bright yellow rock that burned, and saltpetre, a salt made from animal waste that could transform other minerals.


A mixture of sulphur, saltpetre, and charcoal burns vigorously, in a way that none of its individual components will. It didn’t take long for engineers to work out how to contain the reaction and turn it to military ends. A bamboo pipe, sealed at one end and filled with gunpowder became a fire lance, a sort of early flamethrower. When metal and porcelain fragments were added to the gunpowder in a fire lance, the flying shrapnel made it even more dangerous. Eventually weapons were conceived in which the projectiles did far more damage than the eruption of flame and in the thirteenth century the gun was born.

How gunpowder got to Europe is not clear. It may have been brought by Mongol invaders, [7] who had conquered China and then gone on to establish an empire that stretched into central Europe. Roger Bacon[8] wrote down the first European description of gunpowder in 1267 and by 1346 King Edward III had primitive cannon at the Battle of Crécy.


From Crécy it took another 150 years of incremental change in the manufacture of cannons and balls and the formulation of gunpowder for Edward’s primitive cannon to become the devastating weapon that Charles brought to San Giovanni.

Charles’s grandiose plans to take Naples, Constantinople, and become emperor in the East ultimately came to nothing. He was forced to withdraw from Italy and narrowly escaped back to France. He was dead three years later, but gunpowder was here to stay.

Gunner Takes All

Cannon and gunpowder were expensive to produce but the rewards were huge. Those rewards went to whomever could muster the largest army. Individual skill in combat became less important than sheer numbers of people and guns. With city walls no longer a useful defence, city states started to come under the influence of kings and emperors and power began to centralise. It became increasingly difficult for the private armies of the Middle Ages to survive against the massed forces wielded by these newly powerful overlords. Loyalties shifted from the local baron to king and country. Nations were born.

As nations grew they needed bigger and bigger armies, at greater and greater expense. Gunpowder didn’t just undermine the physical barriers that protected city states; it undermined the social and economic barriers that separated the aristocracy from the rest.

In the Middle Ages, position in the aristocratic pecking order was everything. If you were born into a high-status family, you stayed there for life. If you were born in the dirt, you lived in the dirt and died in the dirt. Money was irrelevant to this scheme. A wealthy trader ranked just as lowly as a landless peasant.

The arrival of gunpowder suddenly meant that money mattered. Power no longer came from physical strength but from the barrels of expensive cannon. Merchants were no longer to be ignored, or sneered at, but encouraged and, of course, taxed. The Church’s ban on usury, charging interest on loans, and its appetite for fixing “just” prices were incompatible with the need to grow commerce. The old rules of the Church became less relevant.

From Power to Superpower

Gunpowder blasted open new frontiers in Africa, the Americas, and the East Indies and nations became empires. The returns on firepower were high, spurring the development of smokeless powder and high explosives like dynamite and TNT. The logical finale of this escalation came at the end of the 20th century. Increasing explosive firepower culminated in the development of the atomic bomb at the end of World War II and the nations of the world coalesced around two vast superpowers, the United States and the Soviet Union.

The same logic that undid the 15th century Church’s grip on economic life was at work 500 years later in the Cold War. The contest to build the biggest collection of the most expensive weapons ultimately come down to commercial arrangements. It turned out to be more effective to tax half the wealth of a relatively free economy than to take the entire output of a planned economy. Ultimately the Soviet Union couldn’t afford to keep up with the aircraft carriers and stealth bombers and Star Wars lasers and the empire collapsed, leaving the United States as the dominant military force on the planet.

The centuries-long logic of increasing firepower has exhausted itself. The two superpowers created weapons that are literally too dangerous to use. Nuclear weapons haven’t been used since the bombings of Hiroshima and Nagasaki in 1945. Shifts in technology are swinging the advantage back to the defender. Explosives in the form of Stinger missiles and car bombs or “improvised explosive devices” are now the weapon of choice against superpowers.

For all it’s world-dominating firepower, the United States has been fought to a stalemate in the deserts and mountains of Afghanistan. The most-damaging attack on the U.S. in recent times was delivered by stolen aircraft, used no explosives, and cost next to nothing. More devastating future attacks are likely to be delivered wirelessly or on a USB memory stick.


[1] (Castello di Monte San Giovanni Campano, 2018)
[2] (Davidson & Rees-Mogg, 1997), p38
[3] (Keegan, 1993)
[4] (Oldenbourg, 1966), pp102-5
[5] It wasn’t until 1871 that Germany was finally united.
[6] (Kelly, 2004)
[7] (Chase, 2008), p58
[8] (Roger Bacon, 2018)
[9] (Kelly, 2004)


Castello di Monte San Giovanni Campano. (2018, June 29). Retrieved from Wikipedia:

Chase, K. (2008). Firearms: A Global History to 1700. Cambridge: Cambridge University Press.

Davidson, J. D., & Rees-Mogg, W. (1997). The Sovereign Individual. New York: Simon and Schuster.

Keegan, J. (1993). A History of Warfare. London: Hutchinson.

Kelly, J. (2004). Gunpowder. New York: Basic Books.

Oldenbourg, Z. (1966). The Crusades. London: Phoenix.

Roger Bacon. (2018, July 31). Retrieved from Wikipedia:

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