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St Michael's Mount Castle

In the civil parish of St Michaels Mount.
In the historic county of Cornwall.
Modern Authority of Cornwall.
1974 county of Cornwall.
Medieval County of Cornwall.

OS Map Grid Reference: SW51472982
Latitude 50.11650° Longitude -5.47816°

St Michael's Mount Castle has been described as a probable Timber Castle, and also as a certain Masonry Castle, and also as a certain Artillery Fort, and also as a certain Fortified Ecclesiastical site.

There are masonry ruins/remnants remains.

This is a Grade 1 listed building protected by law*.


It is generally accepted that the summit of the Mount was first provided with stone-built defensive structures at the end of the 12th century when, in 1193, "Henry de Pomeray took possession... in John's name, fortified it and expelled the monks" (Fletcher 1951, 24). He, or Richard I, after his release and Pomeray's suicide, could well have been responsible for the main elements of the castle's layout, in particular the square towers (typically 12th century) at each end of the main western entrance range (91531) and the lesser square towers behind them to the SE (91532 and 91533). These features form the core of the castle and have the priory (91515) safely behind them although even this was fortified, the church tower battlemented and the court walls crenellated. Although post-medieval and 19th century residential improvements have substantially altered the rectangular towers and the range, more survives of the medieval castle than is usually thought. The massive buttress projecting from the southern end of the outer western face of the principal northern tower was probably part of a substantial entrance or gate-house. The well-preserved flight of steps (91530) would have run through it. To the south of these steps was a large building (91529), now almost completely levelled, a possible third and outer gatehouse. Further west still are the footings of a well- built curtain wall, part curvilinear, part rectilinear (91550). Other fragments of probably medieval curtain wall survive to the north, east and south-east of the castle (91551-91553). Although the Mount returned to the peaceful activities of the priory after Pomeray's removal it seems that a military role, but not necessarily a garrison as such, was maintained; the priory (and presumably Mont St Michel, the parent Abbey) was aware that it needed to be able to protect itself. The state too would have benefitted from the strategically useful Mount being defensible and in 1338, while preparing for war with France, King Edward III dismissed Ralph Bloyan from the castle and replaced him by Reginald de Boterels (Botreux) and John Hamly, Sheriff of Cornwall (Taylor 1932, 116). As it was the Mount saw no further military action until the later 15th century. In 1472 John de Vere, the Lancastrian Earl of Oxford, seized the mount by entering with either 80 or 400 men (accounts differ), disguised as pilgrims. The siege which eventually saw Oxford out was intense (see Taylor 1932) and was probably the spur which led to the increased fortification of the Mount including the throwing up of breastworks (91554) around its cliffs and the placing of cannon at its summit. Adaptations of the castle's defences would have continued through the centuries, right down to the Napoleonic Wars when several batteries were placed at the summit and around the island. The core of the castle, however, seems to have remained largely unaltered with the only major change the abandonment of the western gates and buildings during, or more likely, some time before the Civil War. (National Trust HBSMR 91527)

The Mount will still have had some strategic importance in the later medieval period, especially during the French wars, and there was an important harbour to protect. Nevertheless, it is likely that it was as a symbol of power that the Mount attracted military effort. The several actual skirmishes and sieges it witnessed, from Henry de la Pomeray's seizure in 1193 to the wild attack during the Cornish Rebellion in 1549, all have an underlying theme; attempting to gain or retain a symbol of regional or national power. The true military worth of the place was perhaps accurately summed up in John Taylor's derisive words soon after the uninspiring Royalist surrender of it in 1646: it was "not worth the taking or keeping" (Taylor 1649, 16). The castle itself, a strong square granite tower at each end of the western wall and at least two more square towers behind, has never been closely recorded but more survives of the original structure than is often believed. Viewed from the west, with 18th and 19th century accretions imagined away, it is a handsome structure; seen from the south, from 150 feet below almost vertical cliffs, it is awesome. This was an important castle and deserves more attention from both archaeologist and historian.
Fragments of what seems to be a medieval curtain wall - enclosing the flight of steps to the castle's main western entrance and linking naturally defensible cliffs just below the summit on the north, east and south sides - were recorded in the recent survey (Herring 1993,99-101). These can only be fully understood when a large-scale plan of the summit showing not just archaeological features but also natural cliffs, scree slopes etc (all of which were made full use of) has been produced. (Herring 1993)
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This record last updated 15/08/2017 15:56:46

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