Originally built on the islet in 1542 on the orders of Sir Henry Cornish, to protect the harbour at St. Aubin's, the tower became a fort during the English Civil War when it was surrounded by a wall. Remodelled in the 1730's and increased in size the fort rapidly declined following the Crimean War. These days visitors can access the islet by foot at low tide to see the German fortifications which were added in the Second World War during the occupation of Jersey.