[3] Before the building of the castle, Bridgwater was much smaller, but after the granting a licence to crenellate by King John, in 1200, charters for the creation of a borough and a market rapidly followed, effectively creating the heart of a new town.

[4][5] Initially Bridgwater faced competition from the established nearby port of Downend, protected by Down End Castle, but the new settlement rapidly became dominant.

In addition to a keep, located at the south-east corner of what is now King Square,[10] documents show that the complex included a dungeon, chapel, stables and a bell tower.

After the short war, the crown again occupied Bridgwater until 1326 to prevent Roger Mortimer, 1st Earl of March using it as a base for operations if he should escape from custody or return from exile in France.

[16] Some of the external walls of Bridgwater Castle were demolished in the early 1630s by the then owner Henry Harvey, an attorney of the Court of Common Pleas, to build his new house.

[18] In 1642, however, the English Civil War broke out between supporters of Charles I and Parliament: the town and the castle were still seen as having value and a garrison was established by the Royalists under Edmund Wyndham.

[23] The 18th century historian John Collinson suggested that the castle itself was deliberately destroyed the following year, when parliament ordered that the garrison was disbanded.

[25] During the Monmouth Rebellion of 1685 rebel troops were hemmed in at Bridgwater on 3 July, and were ordered to refortify the town, prior to the Battle of Sedgemoor.

[16] In 1721 the remains of the castle, the house and the land was sold to James Brydges, 1st Duke of Chandos who developed an industrial centre in the town and demolished the last of the buildings.

In 2008, during sewer renovation work, a section of the curtain wall of the castle and a tunnel used to transport goods from the port were discovered.