Very Scilly

The Dutch call it the Driehonderdvijfendertigjarige Oorlog, but as that would make our English tongues fall out trying to say it, we call it the The Three Hundred and Thirty Five Years' War between the Netherlands and the Isles of Scilly located off the southwest coast of Great Britain.
It all began in with that lovable character Oliver Cromwell who battled the Royalists to the edges of the Kingdom, or Cornwall as it is also known, and running out of land to retreat to, they jumped on boats and paddled like mad to the Isles of Scilly off the coast of Cornwall which was under the ownership of Royalist John Granville.
The navy of the United Provinces of the Netherlands was at the time allied with Cromwell and the Parliamentarians and when their fleet turned up to give the retreating groups a damn good thrashing, they didn't realise they had canons and sunk several Dutch ships including Merchant ships so the Dutch
demand reparation from the Royalists for the Dutch ships and goods taken by them.
Long story short, the Scilly Islanders told the Dutch to go do one so the Dutch declared war on them but by then the English Navy had turned up and after threatening to canon them back to the stone age, the Scilly Islanders surrendered and the Dutch fleet, no longer under threat, left without firing a shot.
Fast forward to 1986 and the Chairman of the Isles of Scilly Council realised that no peace treaty had ever been signed and sent a letter to the Dutch Embassy in London asking if they were still officially at war with each other, the Dutch looked into it themselves and said 'Ja' so the Chairman invited them over to
officially end the conflict and peace was declared on 17 April 1986, 335 years after the war started.