SHEERNESS-ON-SEA, a seaport, watering-place, naval establishment, and garrison town in the Isle of Sheppey, Kent, is situated on the Thames at the mouth of the Medway, on the Sittingbourne branch of the London, Chatham, and Dover Railway, 52 miles east of London, and 17 north-east of Maidstone. The older part of Sheerness, containing the dockyard, is called Blue Town, the later additions being known as Miletown, Bankstown, and Marinetown. Marinetown consists chiefly of houses occupied by summer visitors, but although there is a good beach for bathing the presence of the dockyard with its surroundings has militated against the success of the town as a watering-place. The dockyard, erected by the admiralty about 1830, was seriously damaged by fire in 1881. The naval establishment is only of the second-class, the basins being too small to admit vessels of the largest size. The dockyard is 60 acres in extent, and contains naval barracks with accommodation for 1000 men. A fort was built at Sheerness by Charles IL, which on the 10th July 1667 was taken by the Dutch fleet under De Ruyter. After this mishap it was strengthened and a dockyard was formed. The fortifications are now of great strength, £100,000 having been spent in adapting them to modern necessities. The town is in the parish of Minster, which possesses the most ancient abbey church in England. The population of the urban sanitary district (area 938 acres) in 1871 was 13,956, and in 1881 it was 14,286.