Brownsea Castle 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 the original invasion scare had passed and was occupied by Parliament during the English Civil War of the 1640s. By the end of the century, however, it had
Brownsea Island island has a heronry, in which both grey heron and little egret nest. There is a large population of non-native sika deer on the island. In the past the numbers have been higher than the island can sustain and have overgrazed. To try to limit damage to trees and other vegetation by deer, areas of the island have been fenced off to provide areas of undamaged woodland to allow other species such as red squirrels to thrive. The lagoon is noted for the large population of common tern and sandwich tern in summer, and a very large flock of avocets