History is messy. Usually, when we talk about the Napoleonic Wars, we focus on grand charges at Waterloo or the freezing retreat from Moscow. But in 1807, something happened that felt more like a modern geopolitical "preemptive strike" than a chivalrous 19th-century engagement. This was the Second Battle of Copenhagen. It wasn't just a skirmish; it was a controversial, brutal, and frankly terrifying display of naval power that saw a neutral European capital go up in flames.
People often confuse it with Nelson's 1801 battle in the same waters. It’s different. In 1801, Nelson famously "turned a blind eye" to signals to retreat. By 1807, the British weren't just looking for a tactical win—they were terrified of a French-dominated Europe and decided to take the Danish fleet by force before Napoleon could. Honestly, it was a move that many in the British Parliament at the time called a "national disgrace."
The Tipping Point: Why the Second Battle of Copenhagen Happened
Napoleon was winning. After the Treaty of Tilsit in July 1807, the French Emperor and Tsar Alexander I of Russia basically decided to carve up Europe between them. The secret catch? They wanted to force neutral Denmark to join their Continental System—a massive trade blockade against Britain.
If Denmark joined, Napoleon would control the entrance to the Baltic Sea. Even worse, he’d get his hands on the Danish Navy. To the British Cabinet, led by the Duke of Portland, this was a nightmare scenario. They didn't have proof that Denmark would join Napoleon, but they weren't willing to wait and find out. George Canning, the Foreign Secretary, sent a massive force to the Baltic with an ultimatum: hand over your entire fleet for "safekeeping" or we take it by force.
Denmark, understandably, said no. They were caught between a rock and a hard place. If they gave the ships to Britain, Napoleon would invade from the south. If they kept them, Britain would attack from the sea. They chose to fight.
A City Under Fire
The British didn't just sail in and shoot at ships. They landed an army. Under the command of Admiral James Gambier and Lieutenant General Lord Cathcart, about 25,000 British troops landed on Zealand. They surrounded the city. This wasn't a quick naval duel; it was a full-blown siege.
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From September 2 to September 5, 1807, the British unleashed a bombardment that the world hadn't really seen before. They used Congreve rockets. These were early, unpredictable, and devastatingly effective at starting fires. Over 1,000 buildings in Copenhagen were destroyed. The Church of Our Lady (Vor Frue Kirke) was gutted.
You have to imagine the chaos. A civilian population trapped in a medieval city while high-tech (for the time) incendiary rockets rained down. It was "total war" before that term was even coined. Roughly 2,000 civilians died. For three days, the sky was orange. The Danish commander, Ernst Peymann, finally surrendered to save what was left of the people.
The Looting of the Danish Fleet
Once the city surrendered, the British didn't just leave. They took everything. They seized 18 ships of the line, 11 frigates, and dozens of smaller vessels. They literally emptied the Danish naval arsenals.
It was a heist on a national scale.
The British took the ships back to Portsmouth. Interestingly, many of these ships weren't even that useful to the Royal Navy. They were built for the shallow Baltic, not the rough Atlantic. But that wasn't the point. The point was that Napoleon couldn't have them. The Danish fleet ceased to exist in a matter of weeks.
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Geopolitical Fallout: Was it Legal?
This is where the Second Battle of Copenhagen gets really controversial in history books. In 1807, there was no Geneva Convention, but there was a "Law of Nations." Attacking a neutral power without a declaration of war was a massive taboo.
- The British Defense: They argued it was "self-preservation." If Napoleon got the fleet, Britain would fall.
- The Danish Perspective: It was naked piracy. Denmark had spent years trying to stay out of the conflict.
- The Global Reaction: Russia used the attack as a reason to declare war on Britain.
It basically turned Denmark into a lifelong enemy of the UK for the duration of the Napoleonic Wars. They shifted from being a neutral trader to a dedicated ally of Napoleon, engaging in the "Gunboat War" for years after.
Surprising Details Most People Miss
One of the more interesting footnotes of the battle involves a young officer named Arthur Wellesley. You probably know him as the Duke of Wellington. Before he went to Spain or met Napoleon at Waterloo, he was commanding a brigade at the Battle of Køge (part of the Copenhagen campaign). He routed the Danish militia with terrifying efficiency.
Another weird detail: The British actually paid for some of the supplies they took from the Danish countryside during the siege. They’d burn your capital city to the ground but pay you in gold for your cow. It's a bizarre contradiction of 19th-century warfare.
Also, the Congreve rockets used in the bombardment were the same ones mentioned in "The Star-Spangled Banner" ("the rocket's red glare"). Copenhagen was their first major "success" in terms of destruction, which is a pretty grim legacy.
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The Long-Term Impact on Denmark
Denmark never really recovered its status as a major naval power after 1807. The loss of the fleet led to the national bankruptcy of 1813 and the eventual loss of Norway in 1814. It changed the map of Northern Europe forever.
For the British, it secured the Baltic trade routes. It ensured that the "wooden walls" of the Royal Navy remained the dominant force on the planet. But it came at a high moral cost. Even in London, the Whig opposition was furious. They called it an act of "lawless violence."
What We Can Learn From 1807
The Second Battle of Copenhagen is a case study in preemptive strikes. It shows what happens when a superpower decides that its own security outweighs the sovereignty of a smaller, neutral nation. It wasn't "clean" and it wasn't "noble." It was a cold, calculated move to prevent a worst-case scenario.
When you look at modern international relations, the echoes of Copenhagen are everywhere. The debate over whether you can attack someone because of what they might do is still happening in war rooms today.
Actionable Historical Insights:
- Research the Source Material: If you want the real grit, look for the "Canning Papers" or the diaries of British midshipmen who were there. Their descriptions of the fires are haunting.
- Visit the Site: If you go to Copenhagen today, you can still find marks of the bombardment. The Church of Our Lady was rebuilt, but the event is baked into the city’s identity.
- Compare the Battles: To really get the context, compare the 1801 and 1807 engagements. 1801 was about politics and treaties; 1807 was about total elimination of an asset.
- Look at the Tech: Study William Congreve’s rocket designs. They changed how cities were besieged, moving the target from the soldiers on the walls to the civilians inside.
The event remains a stark reminder that in the heat of a global conflict, neutrality is often a luxury that the dominant powers simply won't allow. Denmark learned that the hard way in the autumn of 1807.