English castles may be broadly divided into two classes — those built by the king to make good his hold on the country and those built by barons and landowners as fortiﬁed residences. The former are generally found at points of military importance on main routes, or inside walled towns to prevent them becoming too independent, while the latter maybe any— where convenient as a headquarters for the baron’s estates.
The principal royal castle in Dorset was Corfe, guarding the gap which leads through the hills to Purbeck. Originally it was a simple Norman structure, with a square tower—keep and a walled bailey, crowning the highest point of its hill. Later, in the thirteenth century, when ideas on castle—building had much progressed, two outer wards were added with boldly projecting towers to give ﬂanking ﬁre along the curtain walls, enclosing the whole hill—top. On all sides but the south-east the steep slope of the hill made attack practically impossible, so that anyone attempting to capture the castle would have been compelled to take the Outer and Middle Wards before he could come to grips with the Norman defences. Corfe Castle was sold into private hands by Queen Elizabeth, and the living quarters in the Inner Bailey were much enlarged to make it a mansion as well as a fortress. Its stonework was so good that it stood up to all attacks by Parliamentary cannon in the Civil War, and it was ﬁnally taken only by treachery. The victors then deliberately wrecked both castle and mansion by blasting with. gunpowder, and left it in the condition in which it stands today.
Royal castles were built soon after the Norman Conquest in Wareham and Dorchester, the only walled towns at that time in the county. They were of the keep and bailey type, and stood inside the south-west angle of the Wareham ramparts and on the site of the present Dorchester gaol. Sturminster Castle, of which little is known, guarded the bridge over the Stout and was in royal hands at least in King John’s time. Gillingham Castle was an earlier royal hunting lodge, which John fortiﬁed.
The greatest baronial castle was that at Sherborne, built by Bishop Roger of Saturn early in the twelfth century. Though the See was moved from Sherborne to Saturn in 1075, the bishop still had large estates in the neighbourhood. The plan of its defences, which were never much altered in later times, shows that military ideas at the time were much less developed than when the outer wards of Corfe were built. The southern wall is not protected by any towers at all, and could not have repelled a serious attack. The defences of the North Gate were unusual, the original approach having been through a barbican with a gate and narrow passage to the drawbridge in front of the gate—house. Later the moat before the main gate was ﬁlled in, and a middle chamber built in place of the bridge. This castle too was defended for the King in the Civil War, and (unlike Corfe) taken by storm. It too was then deliberately ruined.
Digging in the Castle Hill at Shaftesbury has produced ﬁnds of Stephen’s time, and the castle here was probably one of the many temporary ones which sprang up illegally during the wars between that king and Matilda. Powerstock, Chelborough, Cranborne, and Lulworth seem to have been early Norman motte and bailey castles, but Marshwood with its rectangular plan probably dates from about 12.00. Chideock was a late fourteenth century fortified mansion, which was also defended for King Charles and then ruined in the Civil War.
The curious little building known as ‘Rufus Castle’ in Portland cannot have been built by William Rufus. A castle of sorts existed in Portland in the late twelfth century, but the present structure with its walls pierced for hand—guns and its projecting stone brackets for defending the foot of the wall is clearly much later. What we now see is probably a ﬁfteenth century blockhouse built to protect the landing place at Church Ope from enemies and pirates. It looks more like the ‘peel towers’ of the Scottish borderlands than an ordinary castle. At Woodsford, on the Frome four miles below Dorchester, the modern maps mark a castle, but prints of the building which stood here show it to have been an unfortified manor- house. There may have been an earlier and genuine castle on the site.