Brownsea Castle the castle also has four cannons, probably dating from the 17th or early 18th century. The castle is protected under UK law as a Grade II listed building. Brownsea Castle Brownsea Castle, also known historically as Branksea Castle, was originally a Device Fort constructed by Henry VIII between 1545 and 1547 to protect Poole Harbour in Dorset, England, from the threat of French attack. Located on Brownsea Island, it comprised a stone blockhouse with a hexagonal gun platform. It was garrisoned by the local town with six soldiers and armed with eight artillery pieces. The castle remained in use after
Brownsea Castle another device in 1544 to further improve the country's defences, particularly along the south coast. The castle was built on the south-east corner of Brownsea Island between 1545 and 1547 to protect the entrance of the busy Poole Harbour. The island belonged to the Crown, having been confiscated from Cerne Abbey during the Dissolution of the Monasteries a few years before. It was a conservative design, being a one-storey, square blockhouse, reported in 1552 to be across, able to support guns on its roof and sub-divided into three rooms; the blockhouse was originally intended to have been two storeys in