Which two countries technically remained at war for 335 years because they forgot to sign a peace treaty?

Question

Accepted Answer

The Netherlands and the Isles of Scilly

In 1651, during the tail end of the English Civil War, the Netherlands found itself drawn into the conflict on the side of the Parliamentarians against the Royalists who had retreated to the Isles of Scilly, a small archipelago off the southwestern tip of Cornwall. Dutch ships were being harassed by Royalist privateers operating from the islands, so the Dutch ambassador declared war specifically on the Isles of Scilly in March 1651—not on England as a whole, which was already in chaos.

The Royalists were expelled from Scilly just three months later, but in the flurry of treaty-making that followed the civil war's end, no one remembered to draft a peace agreement between the Dutch Republic and this tiny cluster of islands. The war simply slipped through the cracks of history. Both sides forgot about it entirely.

The oversight came to light in 1985 when Roy Duncan, a historian and chairman of the Isles of Scilly Council, wrote to the Dutch embassy in London to investigate the peculiar rumor. The Dutch government confirmed that, technically, the state of war had never been formally ended. On April 17, 1986, the Dutch ambassador flew to Scilly to sign a peace treaty, finally closing the books on what is recognized by the Guinness Book of Records as the world's longest war.

Why does this matter? It's a delightful reminder that bureaucracy can outlast memory, and that the formal machinery of statehood—declarations, treaties, diplomatic recognition—can persist long after the human reasons for them have vanished. The 335-year war also highlights how peculiar the English Civil War truly was, with its localized allegiances and forgotten footnotes, and how the modern nation-state system we take for granted is still relatively new, full of inherited quirks from messier times.

The treaty that ended a war—but no one signed it