Defending England's Shores

English Heritage

Pendennis Castle and St Mawes Castle, Cornwall

Pendennis and St Mawes: Brothers in Arms
Pendennis Castle (top right, flying the Royal Standard) and its partner St Mawes Castle (flying the flag of St George) face each other across Falmouth Haven, in Cornwall. For over 400 years they kept watch for approaching ships, sometimes friendly but sometimes not.

Enemies on the horizon

St Mawes Castle: enchanting and deadly.

For 350 years its garrison watched the sea and kept its guns ready, waiting to defend against all who would bring violence.

Silent now, but mighty once

Pendennis Castle, with walls of unyielding granite, was raised in 1540 to defend the important estuary of the river Fal.

Its squat tower and encircling lower ‘chemise’ supported a battery of artillery to bombard hostile warships attempting to enter the river.

Symbols of power

Both castles are the work of Henry VIII’s men, at a time when England was isolated and facing invasion from a European coalition.

Warlike and defiant, Henry ordered the building of coastal gun forts on the south and east coasts.

With an innovative circular design, they also carried propaganda - the royal arms of Henry VIII, projecting Tudor power.

The old and the new

Though innovative and designed especially for guns, the castles also harked back to a glorious medieval past.

This was reflected in the older deterrents of castellation (defensive battlements), portcullis and drawbridge.


The castles were periodically adapted to face new threats and to fulfill new military purposes.

Here, a storehouse that supplied the Duke of Wellington’s army in Portugal and Spain is dwarfed by the austere functional Edwardian barracks for the artillerymen stationed at Pendennis.

Command and control

During the Second World War, the Fal estuary was heavily defended by land, sea and air. Pendennis Castle formed the headquarters from which the response to any attack was coordinated.

Here is the Battery Observation Post, where a few vigilant souls watched the horizon and guided the guns of Half Moon Battery to their targets.

Weapons of War
Throughout their history, Pendennis and St Mawes Castles were artillery forts. Their guns and gunners defended the coast and Falmouth harbour.​

Martial ambitions

Henry VIII began this process, equipping his warships, forts and armies with hundreds of guns and seeking expertise in their manufacture from all over Europe.

This is a design for a castle in Kent in 1539.

Italian expertise

Henry VIII’s demands for guns could not be met entirely in England. Many were imported from Italy and the German states, while craftsmen were paid to set up in England.

This mid 16th-century bronze gun at St Mawes was made in Italy by a family of gunsmiths, the Alberghettis.

Homegrown, cast iron

In the 1540s, Henry’s encouragement of the production of guns at home paid off, and guns using cast iron were produced successfully in the Weald of East Sussex and Kent.

By the end of the century, English cast guns were regarded as the finest in Europe - like these replicas at Pendennis.

Nine guns at the ready

By the late 18th century, casting guns in iron was routine.

Nine Gun Battery at Pendennis was a formidable group capable of sinking any hostile ship in the estuary. It was able to fire down from a protected position on the castle ramparts.

Little smashers

Appearances can be deceptive... These stubby 'carronades' - invented by the Carron Company in Scotland in the 1770s - packed a massive punch and could inflict heavy casualties at short range.

They fired larger gunpowder charges than normal, devastating over short distances, when ships closed with each other or for the defence of a fortress when soldiers were attempting to scale the walls.

A Simple Little Change

Guns on heavy wheeled carriages were awkward to move and aim, and crews might only manage one shot before a ship went out of view.

The 1780s invention of the traversing carriage, like this one at St Mawes, solved this problem. The carriage pivoted at the front and rotated on small wheels and an iron rail at the rear. It was easy to move and aim sideways and could be fired more quickly, so fewer guns were needed.

Technological breakthrough 1: rifling

The 19th century witnessed many innovations in gun-making. Foremost was the making of rifled guns that had barrels with multiple internal helical grooves.

On firing, studs or bands on the shells expanded to fill the grooves, causing the shell to spin rapidly.

The result was greater stability, accuracy and power. These Armstrong-Fraser guns at Pendennis, for shells of 64lbs weight, date from the 1860s.

Technological breakthrough 2: breech-loading

The 1890s brought a safe and reliable method for loading guns from the rear, or breech, instead of the front, or muzzle. This made guns much quicker to load and fire.

This gun, at Pendennis, fired a shell of 12lbs weight and was designed especially to combat small fast ships carrying torpedoes and machine guns.

Still working today

The guns of Pendennis form a working collection, illustrating the development of the guns defending our shores from 1540 until 1956.

Some are still fired during public demonstrations in the summer months.

Pendennis in the World Wars
The castle continued to be of strategic importance through the twentieth century

Edwardian expansion

The new Royal Artillery Barracks at Pendennis Castle were begun in 1901 to accommodate a permanent garrison of artillerymen whose role was to defend the important port of Falmouth.

By this time, artillery training had become more technical and professional.

Not exactly luxurious

The barracks accommodated men of the Royal Artillery while they were in training, or working in the active gun crews at Half Moon Battery. This reconstructed room gives an idea of conditions for the ordinary men: clean, tidy, spartan.

Lots of men who trained at Pendennis in the First World War served abroad. Many never came back.

Report to the guard room

A guard was maintained round the clock at Pendennis, and everyone arriving or leaving had to report to the guard room for security.

Here, it is reconstructed to the period of the First World War.

Many soldiers who committed minor breaches of discipline might find themselves in the guard room on a charge, on 'fatigues' or and perhaps confined in the cells for a short time.

Pendennis 1944

In the Second World War, all of Pendennis headland was fortified and occupied with guns, searchlights, barracks, offices and cookhouses.

Though some of these were removed after the war, many survive – notably the Royal Artillery barracks and Half Moon Battery.


Deep underground at Pendennis is the magazine for Half Moon Battery, where ammunition was safely stored in controlled conditions. This is the cartridge store. Cartridges of very dangerous high explosive were kept here before being sent up to the guns above on special lifts.

A cartridge was placed in a gun behind the shell: firing it propelled the shell towards its target.

Dangerous up to 8.5 miles

The last guns in service at Pendennis were in Half Moon Battery.

These are six inch guns (meaning that the shells loaded into it were six inches in diameter) that fired a shell weighing 100lbs at targets up to 8.5 miles away, using data generated by radar.

The guns there today have barrels made in 1946. The gun pits and protective gun house date from the Second World War.

Look up! A new threat

In the First World War, a new danger emerged which brought death from the sky – the airship and airplane. Anti-aircraft (AA) guns were slowly developed in response.

In the Second World War, light AA guns were emplaced at Pendennis, like this 40mm Bofors gun. It was designed for shooting down aircraft attacking at low altitudes.

Echoes of the past

The army is long gone from Pendennis Castle but occasionally events are held to mark a continuing connection with its military past.

Credits: Story

Paul Pattison, Ian Leins, Rose Arkle

Visit Pendennis Castle

Credits: All media
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