part of the fleet that drove off the Spanish Armada in 1588. There are no on-site remains of the Tudor Dock and Yard. Seventeenth century Naval shipbuilding at Portsmouth recommenced under the English Commonwealth, the first ship being the eponymous Fourth-rate frigate Portsmouth launched in 1650. (Portsmouth had been a parliamentarian town during the civil war). A resident Commissioner was first appointed in 1649 (fifteen years later the Commissioner was provided with a house, and extensive gardens, at the centre of the yard). A new double dry dock (i.e. double the standard length so as to accommodate two ships at once) was built by the Commonwealth government in 1656, on what was then the tip of land at the north-west corner of the yard. It was joined by a single dry dock, just to the south; the yard's one shipbuilding slip (completed in 1651) stood between the two docks. These would all have been built of timber, rather than stone. By 1660 the dockyard had, in addition to these large-scale facilities for shipbuilding and repairs, a new ropery (1,095 ft in length) and a variety of small storehouses, workshops and dwellings arranged around the site, which was now enclosed by a wooden palisade. After the Restoration, there was continued investment in the site with the building of a new mast pond and mast house in the 1660s. Dummer's pioneering engineering works As France began to pose more of a military threat to England, the strategic importance of Portsmouth grew. In 1689, Parliament ordered a new dry dock to be built there, large enough to accommodate the latest first-rate and second-rate ships of the line (which were too big for the existing docks). Work began in 1691; as with all subsequent extensions to the dockyard, the new works were built on reclaimed land (on what had been mud flats, to north of the old double dock) and the civil engineering involved was on an unprecedented scale. The work was entrusted to Edmund Dummer, naval engineer and surveyor to the Navy Board. His new dry dock (the "Great Stone Dock" as it was called) was built to a pioneering new design, using brick and stone rather than wood and with an increased number of 'altars' or steps (the stepped sides allowed shorter timbers to be used for shoring and made it much easier for shipwrights to reach the underside of vessels needing