Hostilities broke out in 1651 between the Netherlands and the Isle of Scilly. While the details are a bit sketchy, it appears that Dutch Admiral Maarten Harpertszoon Tromp arrived at Scilly to demand compensation for damages incurred by Dutch ships during the Second English Civil War. Scilly was the last holdout for the royalists, so Tromp expected his demands would be met there.
When his demands fell on deaf ears, Tromp declared war on the Isle of Scilly on behalf of the government of the Netherlands on April 17, 1651.
Before hostilities could commence, the royalists surrendered to England, ending the Second English Civil War and bringing the Isle of Scilly under English authority. Since the Isle of Scilly no longer officially existed as a sovereign nation, Netherlands did not feel an urgent need to follow up on its declaration of war.
With no navies preparing to attack each other, the war soon slipped from everyone’s minds … for 335 years.
It was in 1985 that Roy Duncan, Chairman of the Isles of Scilly Council, brought it to the attention of the Netherlands’ ambassador to the United Kingdom that a state war still existed. The embassy staff went searching through their records and discovered, much to their surprise, that they were, in fact, at war. On April 17, 1986 — on the 335th anniversary of the declaration of war — Dutch Ambassador Jonkheer Rein Huydecoper came to Scilly to sign a peace treaty, officially ending hostilities. He said, “It must have been harrowing to the Scillonians to know we could have attacked at any moment.”
Although this goes down as one of history’s longest wars, it happily was the least destructive, since no property was seized or destroyed, and no blood was shed.
In the end, if you have to fight a war, this is the way to do it.