Tattershall’s first documented castle grew from a manor held by the de Tateshale family. In 1231 Henry III granted Robert de Tateshale permission to fortify his residence, probably authorizing a hall, private chambers, chapel, service buildings, curtain wall, gatehouse, and moat. Little of that thirteenth-century complex remains above ground, but its layout influenced the later castle. The site stood near the River Witham and waterways leading toward England’s east-coast ports, placing it within a landscape of trade, agriculture, travel, and aristocratic control.

Ralph Cromwell, third Baron Cromwell, inherited Tattershall in 1419 and transformed it during the 1430s and 1440s. As treasurer of England under Henry VI, he possessed the income and political ambition to create a residence that projected status rather than merely resisted attack. The four-story Great Tower used hundreds of thousands of locally made bricks at a time when elite English buildings were still commonly faced in stone. Vaulted rooms, large windows, fireplaces, and carved purse emblems advertised Cromwell’s office, wealth, and access to international craft traditions.

The castle formed the center of a wider planned complex. Moats controlled movement toward the tower, while a collegiate church, grammar school, almshouses, market, and service buildings connected lordship with religion and local society. After Cromwell died without a direct heir in 1456, ownership passed through relatives and the Crown. Edward IV, Henry VII, Margaret Beaufort, Henry VIII, and Charles Brandon were among those linked to the estate. A 1545 inventory records rich furnishings and imported textiles, showing that the great brick tower remained a palace as well as a defensive symbol.

Tattershall was generally held for Parliament during the Civil Wars, although Royalists briefly occupied it in 1643. After Charles I’s defeat, surrounding defensive structures were slighted while the Great Tower survived. Absentee ownership and neglect then reduced the complex to a romantic ruin. Floors failed, windows disappeared, the moats were filled, and part of the ground floor served agricultural purposes. The Fortescue family offered the property for sale in 1910, and its carved fireplaces were removed in 1911 for export, provoking a prominent conservation campaign.

George Curzon purchased the castle, recovered the fireplaces, and returned them in a celebrated procession in 1912. Architect William Weir directed repairs, archaeological investigation, and restoration of the moat system according to emerging conservation principles. The rescue influenced debate surrounding the Ancient Monuments legislation of 1913. Curzon bequeathed Tattershall to the National Trust in 1925. The surviving tower and earthworks now reveal both a fifteenth-century experiment in brick architecture and an early twentieth-century argument about whether nationally important buildings could be dismantled and sold as architectural salvage.