The earthwork remains of a 12th century motte and bailey with a stone keep, last documented in 1216. The motte is 250 feet in diameter and 120 feet across at the top. The surrounding ditch, now mostly filled in, is best preserved to the south south west where it is now about 70 feet across and 22 feet below the top of the mound. (Pastscape)
The place was of importance in Saxon times. King Beorhtric, who married Offa’s daughter Edburh, and was poisoned by her, was buried at Wareham in 800.
But we do not hear of this part of Wessex till the time of Alfred, when, in 876, the army of Guthrum, the Danish King of East Anglia, suddenly came down on Wareham, having marched thither through the whole breadth of the land, perhaps to meet their fleet in Poole harbour. They arranged a peace, however, at the time with Alfred, and retired to Exeter, but broke the treaty next year, when they sailed round with a large fleet to Swanage, near Wareham; here in a great storm 120 of their ships were wrecked and the Danes then made a new treaty with Alfred. They came again marauding in 998, and in 1015 Canute came up the Frome, plundering and murdering, and in the end subdued the kingdom of the West Saxons. Wareham Castle is the only one mentioned in the Domesday Survey in this county, therefore by that time the wooden castle on the Saxon burh may have been replaced by a Norman one of stone. Here was confined Duke Robert of Normandy, and the castle is also famous as the scene of the imprisonment and death of Robert de Beleme, son of Roger, Earl of Montgomeri, who came over .with Duke William, described as “the greatest, the richest, and the wickedest man of his age”, “the Devil of Beleme” (see BRIDGEWORTH, SHROPSHIRE). Henry I.,
against whom he rebelled, brought him from Normandy and confined him here, where he starved himself to death or otherwise died.
In the war between Stephen and the Empress Maud both town and castle were taken and retaken more than once. The Earl of Glo’ster embarked here in 1142, when on his way to Anjou, and his son William was Governor of Wareham when the place was taken by Stephen. The Earl, however, retook it after a siege of three weeks, and then strengthened both it and Corfe Castle. It was at this time, too, that Glo’ster took the other Dorset castles of Portland and Lulworth, and probably built the Bow and Arrow, or Rufus Castle, in Portland. In 1153, Prince Henry landed here with 3000 foot and 140 knights to attack Stephen and relieve Wallingford, his first act being to take Malmesbury Castle. King John was here four times, in all for fifteen days, and during one of his visits in 1213 perpetrated one of his barbarous acts. Peter of Pontefract, a hermit, had prophesied that John would be deposed on Ascension Day that year, and after the day had passed, by the King’s order he was dragged about the streets here at the tails of horses, and hanged and quartered. Wareham was long a noted seaport, and until about 1558 fair-sized ships reached its quays. The manor was vested in the Crown from early ages. Henry VIII. granted it successively to three of his wives for their lives—which were short. ‘Then James I. gave it to two individuals, Thomas Emmerson and R. Cowdal, and by the end of the seventeenth century the whole manor had been repurchased and parcelled out.
The fortress, of whose form and building there seems to be no record, together with the town, changed hands more than once during the war of the King and Parliament. In August 1642, at the beginning of hostilities, a Royalist force wrested the castle from their enemies, but it was retaken in the succeeding February. In April 1644 another strong King’s party, under Colonel Ashburnham and Lieutenant Colonel O’Brien, a brother of Lord Inchiquin, attacked and took it with the small loss of two killed and five wounded, when Prince Maurice added a force of 500 men to the garrison. In the following June it was summoned by Essex in vain, and in August, Sir Astley Cooper came before it with 1200 horse and foot, and gained the outworks, and the place was at once surrendered upon articles. The fact then transpired that Lord Inchiquin, having joined the side of the Parliament, had effected the desertion and surrender of his brother. In March 1645 a vote of the House was passed for the “slighting” and demolition of Wareham, this castle not being required now as a check upon Corfe, which had fallen. The western ramparts obtained the name of “Bloody Bank” after Sedgemoor, from the ruthless execution there of a number of the victims of Judge Jeffreys, of infamous memory. The site of the castle keep was granted to Sir Christopher Hatton, and passed with the manor of Corte to the Bankes family.
(Castles Of England, Sir James D. Mackenzie, 1896)