 Before the 16th century Southsea was principally composed of small farms, open grassland and undrained marshland (morass), outside the main naval base and the city itself.However the growing expectation of a possible French attack on the naval base led Henry VIII to order the building of Southsea Castle in 1544, adjacent to the channel approaches to Portsmouth Harbour.Southsea was first recorded as a place name in a Royal plan in 1577.