 During the English Civil War between 1642 and 1646, the inhabitants of the Isles had been Royalist supporters of King Charles I, and rebelled against Parliament in favour of Charles in 1648.Tresco became a base for Royalist privateers and Parliament became concerned that the Dutch, then hostile to England, might exploit the situation, or that Royalist Irish forces might use the islands for an attack on England.In 1651 Parliament sent Robert Blake and a naval force to retake the island, which had been fortified by the Royalists.