The Longest Wars in History: The Strange Wars Everyone Forgot to Fight

Robert E. Lee famously said, “It is well that war is so terrible, or we should grow too fond of it.” This might be the closest thing history has to a polite suggestion that humanity should really find another hobby.

Whether terrible or otherwise, war is supposed to be the kind of event that commands attention. Bombs, battles, generals gesturing dramatically at maps—these things tend to be hard to ignore. When two nations declare war, the least we expect is that they keep track of it, the same way we remember birthdays, tax deadlines, and whether we left the oven on.

But what happens when someone forgets? Is a war still a war if both sides wander off, get distracted, and never get around to stopping it? Apparently so. And humanity, being humanity, has a surprisingly rich tradition of starting wars and then misplacing them.

Buckle up as we explore several forgotten wars —conflicts that lasted astonishingly long—not because of fierce combat (because it includes some wars that were never fought), but because nobody remembered to file the paperwork.

The Netherlands vs. Scilly — 1651–1986 — 335 Years

In 1651, the Dutch Republic and the Isles of Scilly managed to stumble into a war during the tail end of the Second English Civil War. Before anyone could fire a shot, the political situation changed, Scilly stopped being its own little quasi-state, and everyone just… wandered home. The war, however, remained technically active, like an overdue library book no one had the courage to admit losing.

This oversight was not corrected until 1986, when a Dutch ambassador finally visited Scilly and formally ended the conflict. One imagines the conversation went something like, “So, uh… sorry we never called.”

Huéscar, Spain vs. Denmark — 1809–1981 — 172 Years

In 1809, the Spanish town of Huéscar boldly declared war on Denmark to show support for Napoleon. This was a dramatic gesture. It was also the administrative equivalent of declaring war on someone by mailing them a strongly-worded postcard and never checking your mailbox again.

After that initial spark of bellicosity, absolutely nothing happened. No battles. No skirmishes. Not even an awkwardly-aimed insult. Both sides simply forgot.

Fast forward to 1981, when a researcher realized Huéscar’s citizens had technically been at war with Denmark for 172 years. This came as a surprise to everyone, especially the Danes, who had spent two centuries being aggressively peaceful.

Huéscar’s municipal government quickly voted to seek peace, which Denmark graciously accepted—probably relieved to learn they were not expected to retroactively participate in a war they’d never heard of. On the anniversary of the original declaration, the two sides met, signed a treaty, and hugged it out. Zero casualties. Exceedingly polite war.

Montenegro vs. Japan — 1904–2006 — 102 Years

In 1904, Montenegro—then a small but enthusiastic kingdom—declared war on Japan to support its ally Russia. This was spirited but strategically awkward, since Montenegro lacked certain essential military assets. Such as a navy. Or any ability to reach Japan.

When the Russo-Japanese War ended in 1905, everyone involved forgot Montenegro had been on the guest list. Montenegro wasn’t mentioned in the peace treaty, which meant the war technically continued, even as Montenegro itself was absorbed into Yugoslavia and, later, reemerged as an independent nation.

Japan and Montenegro only realized the oversight in 2006 while discussing trade agreements—surely the most bureaucratic way possible to discover you’ve been at war for a century. A quick peace treaty fixed the problem, officially ending a conflict that had achieved the rare feat of producing absolutely no combat and no hard feelings whatsoever.

Andorra vs. Germany — 1914–1958 — 44 Years

When World War I began, Andorra wasted no time declaring war on Germany. This made sense—if you’re a tiny European microstate with no standing army, a conflict involving major world powers is definitely your moment to shine.

Andorra contributed three volunteers to the war effort. Germany, for its part, seems to have been unaware of this existential threat. When the Treaty of Versailles was drafted, Andorra wasn’t invited, meaning there was no official mechanism to end the war.

In 1958, peace was finally proclaimed—at least according to newspapers. Modern historians have since tried to confirm whether Andorra ever formally declared war in the first place, only to discover that the documentation may have been lost.

This is not unprecedented. Fiji once misplaced its Declaration of Independence and had to ask the United Kingdom for a photocopy. Nations, it turns out, lose paperwork just like the rest of us.

Costa Rica vs. Germany — 1918–1945 — 27 Years

Costa Rica declared war on Germany in 1918, but was left out of the Treaty of Versailles due to concerns about its then-government. As a result, Costa Rica entered the strange diplomatic limbo of being at war with someone long after everyone else had gone home.

By the time World War II rolled around, Costa Rica still had an unresolved World War I on its hands. Fortunately, the Potsdam Agreement finally settled things in 1945, meaning Costa Rica’s first world war ended only because the second one did.

Allies of World War II vs. Germany — 1939–1991 — 52 Years

May 8, 1945—VE Day—is remembered as the day Germany surrendered, signaling the end of World War II in Europe. Except, not quite. Celebrate, yes. Sign the paperwork, not so much.

Because Germany was occupied and lacked a universally recognized government, not all Allied nations could formally conclude the war. The United States modified its declaration of war in 1949 but kept things technically open until 1951, when President Harry Truman finally issued an official proclamation ending hostilities.

The war, in a legal sense, didn’t fully end for all Allied powers until after German reunification, when a final treaty took effect in 1991. This means some nations were technically at war with Germany longer than Germany actually existed in its wartime form. Bureaucracy is undefeated.

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