for the next sixty years it served as the headquarters of Nore Command, whose Commander-in-Chief was accommodated in the adjacent Admiralty House. In 1897 a new, even longer dry dock was opened on the north side of No 1 Basin: at its opening, this (No 9 Dock) was the largest in the world at long by wide. At around the same time, in the older part of the dockyard, No 7 Slip was extended to accommodate the building of HMS Prince of Wales (launched in 1902), and a new (uncovered) slipway was built a little to the north (No 8 Slip, completed in 1900); at this was one of the longest slips in the world and was designed for building battleships. (The older slipways, by contrast, were proving much too small and they were mostly filled in around this time, their covered areas being put to alternative uses.) The first battleship to be built on the new No 8 Slip was HMS Africa, launched in 1905; however it also proved to be the last, as it was announced (controversially) that Chatham Dockyard would be unable to accommodate Dreadnoughts. Proposals were made for a fourth Basin of , together with additional large docks of up to , to cover the remaining land on St Mary's Island; but these were soon superseded by plans to build an entirely new dockyard at Rosyth. Nevertheless, Light cruisers and other smaller vessels continued to be built at Chatham during the first half of the 20th century. Also with the 20th century came the submarine. The first submarine to be built at a royal dockyard was , launched from the covered No 7 Slip in 1908 and then fitted out in No 2 Dock; five more of the same class followed, C18, C19, C20, C33 and C34. During World War I, twelve submarines were built here, but when hostilities ceased, uncompleted boats were scrapped and five years passed before a further ship was launched. In the interwar years, eight S-class submarines as well as X1 were built at Chatham but this was a period of decline. Production ramped up during World War II with HMS's Umpire, Una, Splendid, Sportsman, Shalimar, Tradewind, Trenchant, Turpin, Thermopylae and Acheron being constructed. Last years In February 1958 it was announced in Parliament that Sheerness Dockyard would close in 1960, with Nore Command (and its Chatham-based Commander-in-Chief) to be abolished the