Three Hundred and Thirty Five Years ' War The Three Hundred and Thirty Five Years ' War ( ) was a theoretical state of war between the Netherlands and the Isles of Scilly ( located off the southwest coast of Great Britain ) . It is said to have been extended by the lack of a peace treaty for 335 years without a single shot being fired , which would make it one of the world ' s longest wars and a bloodless war . Despite the uncertain validity of the declaration of war , and thus uncertainty about whether or not a state of war ever actually existed in the first place , peace was finally declared in 1986 , bringing an end to any hypothetical war that may have been legally considered to exist . The war . Origins . The origins of the war can be found in the Second English Civil War , fought between the Royalists and Parliamentarians from 1642 to 1652 . Oliver Cromwell had fought the Royalists to the edges of the Kingdom of England . In the West of England this meant that Cornwall was the last Royalist stronghold . In 1648 , Cromwell pushed on until mainland Cornwall was in the hands of the Parliamentarians . The Royalist Navy was forced to retreat to the Isles of Scilly , which lie off the Cornish coast and were under the ownership of Royalist John Grenville Dutch Navy alliance . The navy of the United Provinces of the Netherlands was allied with the Parliamentarians . The Netherlands had been assisted by the English under a number of rulers in the Eighty Years ' War ( 1568 – 1648 ) , starting with Queen Elizabeth I of England . The Treaty of Münster ( 30 January 1648 ) had confirmed Dutch independence from Spain . The Netherlands sought to maintain their alliance with England and had chosen to ally with the side likely to win the Civil War . The Dutch Navy was suffering heavy losses from the Royalist fleet based in Scilly . On 30 March 1651 , Admiral Maarten Harpertszoon Tromp arrived in Scilly to demand reparation from the Royalist fleet for the Dutch ships and goods taken by them . According to Whitelocke ' s Memorials ( cited in Bowley , 2001 ) , a letter of 17 April 1651 explains : " Tromp came to Pendennis and related that he had been to Scilly to demand reparation for the Dutch ships and goods taken by them ; and receiving no satisfactory answer , he had , according to his Commission , declared war on them " . As most of England was now in Parliamentarian hands , war was declared specifically upon the Isles of Scilly . Royalist surrender . In June 1651 , soon after the declaration of war , the Parliamentarian forces under Admiral Robert Blake forced the Royalist fleet to surrender . The Netherlands fleet , no longer under threat , left without firing a shot . Due to the obscurity of one nation ' s declaration of war against a small part of another , the Dutch did not officially declare peace . Peace treaty . In 1985 , Roy Duncan , historian and Chairman of the Isles of Scilly Council , wrote to the Dutch Embassy in London to dispose of the myth that the islands were still at war . Embassy staff found the myth to be accurate and Duncan invited the Dutch ambassador Jhr . Rein Huydecoper to visit the islands and sign a peace treaty . Peace was declared on 17 April 1986 , 335 years after the " war " began . The Ambassador joked that it must have been harrowing to the Scillonians " to know we could have attacked at any moment . " Authenticity . Bowley ( 2001 ) argues that the letter in Whitelock ' s Memorials is the probable origin of the " declaring war " legend : " Tromp had no ' Commission ' from his government to declare war on the rebels in Scilly ; but he did come to try — by a show of force , threats and even by violence perhaps , although this never happened — to seek reparation for Royalist piracies , but short of resorting to any action which might offend the Commonwealth . . . . even if [ a war ] had occurred in 1651 , all matters pertaining would have been resolved in 1654 as a part of the treaty between England and the United Provinces at the end of the First Dutch War " .