The Four Days' Battle was a naval battle of the Second Anglo–Dutch War. Fought from 1 June to 4 June 1666 in the Julian or Old Style calendar then used in England (11 June to 14 June New Style) off the Flemish and English coast, it remains one of the longest naval engagements in history. On learning that the French fleet intended to join the Dutch at Dunkirk, the English decided to prevent this by splitting their fleet. Their main force would try to destroy the Dutch fleet first, while a squadron under Prince Rupert was sent to block the Strait of Dover against the French – who did not appear.