Defence against invasion

St Mawes Castle is a four-storey artillery fort, like its counterpart across the bay, and was built in the 1540s as part of the largest national coastal defence programme since the Roman era. It stands solidly above the rocky coast, once a deterrent to hostile ships that might have sought to venture up the river passage.

Against the backdrop of Henry’s break with Rome, England found itself politically isolated. Following a French and Spanish alliance in 1538, and the possibility of an attack on England, the king looked to fortify the south and east coasts. The Fal estuary was one of several locations where the enemy might gain a foothold in England.

We know that in 1537, an important local dignitary, John Arundell, had already petitioned the king to protect the Fal with ‘blockhouses made upon our haven’.  But he had to wait until 1539 and after, when St Mawes was begun as one of 30 new fortifications built by Henry VIII to defend important ports and anchorages around the coast. This flurry of building I became pertinent under the threat of the Spanish Armada half a century later, which sailed close by, and the area continued to be a vulnerable and therefore fortified until after the Second World War.

Wars at St Mawes

The tensions between England and Spain continued in the 1560s - and beyond. Periodically, the castle’s small garrison increased, including during times of crisis such as 1574 when word came of the gathering of a hostile fleet at a Spanish port.

The Spanish threat was to continue, with war formally declared in 1585 and lasting until 1604. In 1588, the great Spanish Armada caused high alert but ultimately sailed past. However, Cornwall was raided by a small Spanish force in 1595 (at Penzance, Newlyn, Mousehole and Paul). In 1596 and 1597 another Spanish Armada set sail for England, with its target Carrick Roads, but was foiled by bad weather.

In 1779, militia were called up during the American War, when another French invasion was expected, and remained on alert at the castle until 1783. St Mawes was again garrisoned between 1793 and 1815 during the French Revolutionary and Napoleonic Wars, with 10 heavy guns (24-pounders) placed outside the castle on a battery close to the shore in preparation for conflict.

World War Two at the Castle

After a lapse in active use the castle was garrisoned again in the Second World War, which brought a flurry of preparations. This included the addition of a twin 6-pounder guns built on the shoreline north west of the castle; these fearsome weapons could launch a hail of shells at a very fast rate of fire against approaching torpedo boats and small warships.

The castle saw especially high alert throughout the spring and summer of 1944, when American troops and equipment arrived for training before D-Day and the invasion of the Normandy beaches. It’s not difficult to imagine the thrum of activity these new arrivals would have brought, with the castle once again buzzing in preparation for conflict. 

Henry’s vision preserved

In 1956, no longer needed because rockets had replaced coast artillery, St Mawes Castle passed to the care of the state in recognition of its exceptional historical importance. Few Henrician artillery forts are so complete and so able to tell the tale of Henry’s vision.

To this day, visitors can still see carvings invoking the castle’s originator:

Semper vivet anima Regis Henrici Octavi qui anno 34 sui regni hoc fecit fieri (May the soul of King Henry VIII, who had this [castle] built in the 34th year of his reign, live forever).