timeline item
Here is the information we have
on the item you selected
More like this
sign up for our newsletter
© 2018 Engineering Timelines
engineering timelines
explore ... how   explore ... why   explore ... where   explore ... who  
home  •  NEWS  •  search  •  FAQs  •  references  •  about  •  sponsors + links
St Mawes Castle
St Mawes, Roseland Peninsula, Cornwall
associated engineer
Not known
date  April 1540 - 1544
era  Tudor  |  category  Castle  |  reference  SW841327
St Mawes Castle was built on the orders of King Henry VIII to repel invaders from France and Spain. It defends the eastern side of the Carrick Roads and Fal Estuary, as well as Falmouth Harbour, while its counterpart at Pendennis safeguards anchorages on the western side. It's a particularly well-preserved example of Tudor architecture.
The castle was constructed as an artillery fort — designed to resist bombardment and allow return of cannon fire. Its thick curved walls would have deflected enemy cannon balls and their relatively low profile would have presented a difficult target for shipborne attacks. However, it is overlooked by hills and would therefore have been vulnerable to land attack.
Construction began in April 1540 and was completed in 1544. In 1599 the castle held a garrison of 100 men.
In March 1646, during the English Civil War, the then governor surrendered the castle to the Parliamentarian army without a shot being fired. Thereafter, a garrison remained in the castle until 1920. Between 1939 and 1946, anti-aircraft guns at the castle defended Atlantic convoys assembling in the estuary. In 1956 troops left the castle for the last time and it was rturned over to the guardianship of the Ministry of Works, which was succeeded by English Heritage in 1984.
In plan the fort is a clover-leaf shaped. A central circular tower some 15m in diameter, with walls almost 3m thick and topped with a lookout turret, rises above three lower curved bastions, known as lunettes. The circular north western and south eastern bastions are 17m in diameter, while the semicircular south western bastion is at a lower level than the others and has a diameter of some 19m. Each bastion has five gun ports. Water was supplied by an on-site well.
The earliest part of the complex is the blockhouse, located south west of the fort at the shoreline. It had three gun ports and originally it was roofed, with more guns mounted on top, but its height was reduced during the 19th century when it was incorporated into the sea-level battery that surrounds the headland.
The masonry, gun loops, windows and heraldic carvings are all of excellent quality — a deliberate display of monarchical power. The walls are inscribed with flattering messages in Latin composed by the king’s antiquary and chaplain, John Leland. A local landowner, Sir Thomas Treffry, volunteered to supervise the building of the castle and was appointed its deputy governor. Michael Vyvyan of Trellowarren was governor or 'first captain'. The office of governor was abolished in 1849.
The central tower, or keep, has four storeys with wall openings designed to accommodate various weapons including handguns and crossbows. However, the most powerful weapons, such as cannons, were mounted on the keep roof and the three bastions. There is a basement kitchen and a ground floor mess room, but otherwise soldiers were expected to sleep alongside their guns. Entrance to the keep is at the third level, through the guardhouse and over a bridge across the dry ditch that would once have encircled the entire fort. The lookout turret had a parapet originally, in the style of the parapets around the keep and bastions, but when it was rebuilt in the 17th century the parapet was replaced with a cupola.
By the mid-19th century, amid fears of French invasion, the Grand Sea Battery west of the castle was rebuilt to allow the mounting of 12 heavy guns. A new magazine was dug at the rear of the battery.
The castle became an ancient monument under state care in 1920 and is now administered by English Heritage. The buildings and grounds are open to the public.
Supervising engineer: Sir Thomas Treffry
Research: ECPK
"The Castles of Devon and Cornwall" by Mike Salter
Folly Publications, Malvern, 1999
"The Castles of Pendennis and St Mawes" ed. Lorimer Poultney
English Heritage, London, 1999

St Mawes Castle