Tenby has the same derivation as Denbigh in North Wales. Anciently it was called Dynbych-y-Pyscod, the “precipice of fishes.” The importance of the town dates from the settlement of the Flemings in the reign of Henry I. In 1150 Cadell, eldest son of Rhys ab Gryffith, was slain by the people of Tenby, in revenge for which the castle was taken and the town devastated by his two brothers Meredith and Rhys. During the Wars of the Roses the fortifications were restored and strengthened by Jaspar, earl of Pembroke. They were again greatly strengthened by Elizabeth in apprehension of the landing of the Spaniards. At the beginning of the Civil-War the town and castle were garrisoned for the king, but in 1644 it surrendered to the Parliamentarians after a siege of three days. Its privileges were extended by Humphrey, duke of Gloucester, who made the mayor an independent justice, and by Henry IV., Henry VI., Elizabeth, and Charles I. It is now governed by the Municipal Act, and the corporation are the sanitary authority. Since the 27th of Henry VIII. it has formed part of the Pembroke district of boroughs for parliamentary representation.