Castles of the British Isles

St Mawes Castle sits on Castle Drive at the south-western corner of St Mawes, on the eastern side of Carrick Roads, the estuary into which empties the rivers Carnon, Fal, Penryn, and Truro. Falmouth and the sister fortress of Pendennis Castle are on the opposite side of the estuary.

Beautifully positioned to overlook that estuary, the castle is amongst the best-preserved of the sixteenth century clover-leaf fortresses of Henry VIII (technically a 'device castle'), and the most elaborately decorated of them all.

The four-storey castle helped to protect Falmouth from invasion, one of many Tudor forts to be commissioned by the king to counter the threat posed by Catholic Europe. Walmer Castle and Deal Castle in Kent are two other such examples (see 'related links', below).

It was probably built by Thomas Treffry of Fowey using local shale, along with some granite and freestone. The work commenced in March 1540, six months prior to work beginning on Pendennis Castle. Treffry reported that he had completed the setting out of the 'fortlet'. Perhaps not fully complete at the time, the fort was garrisoned by December 1540. The work also seems to have included a powerful sea battery beside the old blockhouse.

Treffry’s use of 'fortlet' to describe St Mawes seems to imply that, even at its inception, it was of lesser importance than Pendennis. This potentially-implied pecking order along with its poor siting seemingly set the tone for its future treatment, but it did prove its importance in 1588 when the Spanish armada sailed close by.

Cornwall was raided by a small Spanish force in 1595 which entered Penzance, Newlyn, Mousehole, and Paul. In 1596 and 1597 another Spanish armada set sail for England, with its target being Carrick Roads, but that attempt was foiled by bad weather.

A programme of expansion took place in 1597-1600. Sketch plans of the 1620s show angle bastions which, probably, were added to the castle in the early seventeenth century, as mentioned by engineers Morrison and Ogle in their inspectional report of 1623. They could have been installed to protect the rear of the sea battery below.

Ornamentation includes inscriptions which were carved by the royal antiquary, John Leland. Those verses are described by the Lysons and by Hitchens & Drew in their History of Cornwall.

The castle was maintained by a small company of gunners. During the English Civil War they and their captain surrendered the castle and its thirteen guns to the parliamentarian army on 12 March 1646. The castle was considered to be too valuable to be destroyed. Instead it was re-garrisoned.

It remained in good condition into the early eighteenth century, as noted by Colonel Christian Lilly in his survey. Another survey was carried out by Lilly in 1735, showing little had changed. By that time the small bridge across the moat was supported on two masonry arches.

Militia were called up in 1779, during the American War of Independence, when another French invasion was expected. The castle remained on alert until 1783. It was again garrisoned between 1793-1815 during the French Revolutionary Wars and the subsequent Napoleonic Wars. It served as a barracks for up to seventy men, just in case French forces attempted an ill-advised landing on mainland Britain.

On 21 February 1851 the Board of Ordnance permitted the coastguard to erect a battery in the castle in order to drill the troops. Ammunition was to be stored in a 'small magazine' within the castle.

By 1855 a detachment of Royal Miners Militia Artillery was based at St Mawes to man the sea battery. Twenty men were still stationed there in 1905. The castle remained in military hands during the First World War but by then the garrison appears to have been withdrawn.

It was designated a 'Guardianship Ancient Monument' in June 1920 but re-entered service for the Second World War in July 1941, when twenty-four men of 173 Coast Battery Royal Artillery arrived to man the new battery of six-pounder twin quick-fire guns. It remained on high alert throughout the spring and summer of 1944, when American troops and equipment arrived for training prior to D-Day.

During the 1960s almost all evidence was removed of Second World War works in order to restore its tranquil pre-war setting.

All photos on this page kindly contributed by Guy Fogwill via the 'History Files: Castles of the British Isles' Flickr group.