 Cowes Castle was used to house important visitors to the Isle of Wight and also as a prison ; the captain of the castle had further responsibilities for managing the arrival of foreign vessels . When the English Civil War broke out in 1642 between the supporters of Charles I and Parliament , the castle was initially held for the King by its captain , Humphrey Turney . On 12 August , as tensions between the rival factions on the island increased , Turney personally fired one of the castle 's guns at the nearby Parliamentary naval vessel Lion . An unidentified Scottish naval captain then came ashore on 16 August and captured Turney , before landing more men and taking the castle for Parliament , who held it for the rest of the war . 
