2 Date

A date for construction, or major alterations or rebuilding, will often be found from documentary sources; dates for minor works might be obtained from archaeological evidence of stratification and objects found in excavation, by dendrochronology, and by analysis of standing structures. The tradition of building blockhouses extends over about 250 years, although some towers in existing castles were earlier modified for artillery, as in the Arcade of the western shore at Southampton, Hampshire, in 1360 and Cooling Castle, Kent, in 1381.

There was no constant progression of development in the class itself although there was in the design of gunports. The first blockhouse to be built, Cow Tower, in 1398, was of brick, on an inland site but commanding a river approach, and was of three storeys with the upper storeys pierced for for six guns each. Virtually all other examples overlook the sea or an estuary and are built of stone and are much lower in height; the major period of construction was in the maritime defence programmes of Henry VIII between 1539 and 1545 when a new concept owed little to precedent. The last blockhouse to be constructed, Cromwell's Castle, in 1651, was built after the class had been rapidly overtaken by the new, continental style, earthwork fortifications which are considered as a separate class.