History of St Catherine’s Castle

St Catherine’s Castle is an early artillery fort, probably built during the 1530s. A two-gun battery was added below it in 1855 at the time of the Crimean War, and as late as the Second World War the fort was modified again to form part of a more extensive battery. It demonstrates well how military architecture, technology and defensive tactics developed over a period of 400 years. 

St Catherines Castle seen across the River Fowey estuary from Polruan

St Catherine’s Castle seen across the River Fowey estuary from Polruan

A Tudor Fort

The castle formed part of the comprehensive system of coastal defence begun by Henry VIII after his break with the Church of Rome resulted in England’s isolation from Catholic Europe. It is shown as part of the defences of Fowey harbour on a map of 1540 as ‘half-made’.

The building work was supervised by Thomas Treffry, whose family had played a leading role in the town for several generations. Treffry went on to supervise the building of Pendennis and St Mawes castles in the 1540s, and the design of St Catherine’s seems primitive by comparison.

St Catherine’s Castle takes its name from the rocky headland on which it stands. Its position, high above the entrance to the Fowey estuary, is spectacular: from the terrace there are superb views across the attractive town and harbour.

St Catherine’s Castle was kept in repair throughout the Tudor period and manned during the first English Civil War (1642–6), when Cornwall as a whole declared for the king, but by 1684 it was described as ‘ruinous’.


The 19th Century

In the mid-19th century the fear of invasion returned during the Crimean War, leading to a general refortification of the south coast.

At St Catherine’s a battery for two guns was built on the levelled platform on the tip of the headland below the fort, protected behind a parapet wall. A magazine was built into the rock beside the curtain wall entrance.

The refurbishments were recorded by a series of square granite plaques marked ‘WD 1855’ and fixed onto the curtain wall and bastion.

West, south, east and north elevations of the castle in a scale drawing

West, south, east and north elevations of the castle

Second World War

By the end of the 19th century St Catherine’s Castle had again been abandoned, but it was to be put back into military service once more during the Second World War. From June 1940 St Catherine’s Point became a gun battery and observation post, stretching from the castle itself to the higher ground to the west.

One of the Crimean War gun emplacements became the site for one of two anti-aircraft guns, and a concrete pillbox was built beside it. The magazine beside the gateway was brought back into use to store ammunition and the 16th-century tower served as the firing point for a controlled minefield laid across the mouth of the Fowey estuary.

Most of the 1940s concrete defences were dismantled after the war, bringing to an end this most recent chapter in the military history of the castle.

Looking steeply up to the castle on its rocky promontory

The castle on its rocky promontory


The fort consists of a single D-shaped tower looking south-east from the tip of the headland, from which two sections of curtain wall, pierced by musketry slits, extend downslope to the north-east and south-west.

A bastion projects outwards from the north-east stretch of wall and there is a wide gateway near its north-east end. Both stretches of wall terminate in precipitous cliffs, cutting off a near semicircular area at the end of the headland.

The tower is two storeys high, with walls up to 4 feet 6 inches (1.35 metres) thick. There are two rows of gunports, which cover both the approaches to the estuary and the harbour itself. These gunports have been modified over the years but were originally intended for cannon mounted on flat boards, rather than on wheels.

One of the granite plaques commemorating the 19th-century refurbishments - W D 1855

One of the granite plaques commemorating the 19th-century refurbishments

On the ground floor there are three gunports and a tall, narrow fireplace. At first-floor level there are five narrow windows, which would have been useful as lookout and small arms positions. The one above the entrance is largely blocked, and has a brick oven built into it, now also blocked. There are two gunports at this level, one now blocked.

In one corner of the tower are the remains of a spiral staircase that gave access to the upper floor and roof, which was probably finished off by a parapet. There are no domestic quarters and it is unlikely that there was ever a permanent garrison stationed here.




Further Reading 

Morley, B, Henry VIII and the Development of Coastal Defence (HMSO, London, 1976)



The text on this page is derived from the Heritage Unlocked series of guidebooks, published in 2002–6. We intend to update and enhance the content as soon as possible to provide more information on the property and its history.

An arched stone gunport blocked by courses of flat stone

A blocked gunport

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