WAR ZONE – The Isles of Scilly

10 mins read

MHM Cromwell's Castle (2)David Flitham discovers an off-shore treasure-trove of British military heritage.

Situated some 48km west-south-west of Land’s End, the Isles of Scilly are England’s most southern and westerly outpost. This granite archipelago comprises some 150 outcrops, only five of which, St Mary’s, Tresco, St. Martin’s, Bryher and St. Agnes, are inhabited. Its strategic importance was summed up in 1602 by Sir Francis Godolphin (1540-1608) who stated “no other place can so aptly permit or restrain the traffic of Ireland and the north of Scotland with France or Spain.” And from the middle of the 16th century onwards, national government realised the strategic significance of the islands, heralding 4 centuries of military history, a history that can be traced to this day.

Scilly’s military heritage focuses on the two largest islands, St. Mary’s and Tresco. Before 1548, the only fortification was Ennor Castle, overlooking Old Town Bay on St. Mary’s, probably dating from the 13th century. Whilst traces of the castle were visible in 1756, only a small wooded mound is visible today.

Tudor Defences

The Scilly Isles did not feature as part of the Henrician programme of coastal defences, but this changed during the reign of his son, Edward VI. In 1548, work commenced on Tresco Castle (later named ‘King Charles’ Castle’), a polygonal gun battery for five guns, located on Castle Down on Tresco’s west coast, guarding both New Grimsby harbour and the northern approach to St. Mary’s. At the same time, work commenced on the ‘Old Blockhouse’, on the opposite coast, overlooking Old Grimsby harbour.

MHM The Garrison - Redan B and the Woolpack Battery (3)St Mary’s main harbour is situated on St. Mary’s Pool, on the west of the island, facing Tresco. During the 1550s, construction began on a state-of-the-art bastioned fort overlooking the eastern side of the harbour. Known as ‘Harry’s Walls’, it was never completed. In 1570, Elizabeth I leased the islands to Francis Godolphin, who, in 1593, as a result of the on-going conflict with Spain, built the Star Castle, an eight-pointed star-shaped fort on the Hugh, the headland to the west of St. Mary’s harbour. Two years later, Scilly’s defences were nearly put to the test as in July 1595 Spanish forces landed at Mousehole, close to Penzance on the mainland. Godolphin had realised the threat beforehand (thanks to the warning from an escaped English gunner) and, as deputy Lord Lieutenant of Cornwall, requested reinforcements from Lord Essex. As it was, the Spanish ignored Scilly, concentrating their attacks on Mousehole, Newlyn and Penzance where Godolphin led the defence. Back on St. Mary’s, early in the 17th century, Godolphin constructed a pier for the harbour as well as a curtain wall across the neck of land joining the Hugh to the rest of the island. Not only did this mark the start of the fortification of what became known as ‘The Garrison’, but also the early development of Hugh Town, the capital of the islands.

The Civil Wars

By the 1620s, Scilly’s defences were in need of repair and improvement. Earthworks were built surrounding King Charles’ Castle and the magazine, still standing today (albeit with 18th century alterations), was built by The Garrison gate. Further defences were to be added in the years up to 1651, particularly by the Royalist garrison who made particularly good use of the coastal geography, placing batteries where rocky points occurred, thus making direct frontal assaults very difficult.

MHM Harry's Walls (6)During the first Civil War (1642-46), the Scilly Isles were in Royalist hands, under the governorship of another Sir Francis Godolphin (1605-1667, grandson of the builder of Star Castle). From here a small fleet of Royalist privateers operated and following the final surrender of Royalist forces in the south-west of England in March 1646, it was to Scilly that Charles, Prince of Wales fled. Following Charles’ departure to Jersey, a Parliamentary naval blockade led to the surrender of Scilly. But in 1648, the garrison rebelled against the governor and declared for the King.

Sir John Grenville (1628-1701, the son of Sir Bevil Grenville, who was killed at the Battle of Lansdowne in 1643), was installed as the Royalist governor and under his command, Scilly became a major privateering base, preying on both Dutch and Commonwealth (declared in 1649 following the execution of Charles I) vessels. The Dutch took this threat more seriously than the Commonwealth and a fleet under the command of Admiral Maarten Harpertszoon Tromp was dispatched to deal with the islands (according to Whitelocke’s Memorials “Tromp came to Pendennis and related that he had been to Scilly to demand reparation for the Dutch ships and goods taken by them; and receiving no satisfactory answer, he had, according to his Commission, declared war on them”. Therefore, Scilly was technically at war with the Dutch until 17th April 1986 when 335 years of ‘war’ was brought to an end with a peace treaty between Scilly and the Netherlands). In the end it was the prospect of Dutch occupation of Scilly rather than the action of the privateers which prompted a Commonwealth expedition in April 1651.

Admiral Blake

The strength of the fortifications on St. Mary’s, led the commander of the expedition, Admiral Robert Blake, to rule out a direct assault and instead focused attention on Tresco. Following an unsuccessful initial attempt (soldiers were actually landed on the uninhabited island of Northwethel, close to Tresco), Blake landed on Tresco’s east coast, taking Old Grimsby and its blockhouse before moving inland and striking against Kings Charles’ Castle whose defenders chose to blow it up to prevent its capture. By 20th April 1651, Tresco was in Blake’s hands. He established a battery at Carn Near, the southern-most point, from which he could bombard St. Mary’s Pool and harbour (not without incident, however, as the first cannon to be fired exploded, and Blake narrowly avoided serious injury). With the harbour now under bombardment and with assault imminent, on 5th May, Grenville surrendered.

MHM Old Town Churchyard (2)Following its capture, many of Scilly’s existing fortifications were maintained, whilst on Tresco, a new fortification was erected in 1651/2, immediately below King Charles’ Castle. What became known as ‘Cromwell’s Castle’, it was a tall, round rubble-built gun tower, with an appearance that appears to anticipate the later Martello towers. It is a two-storey tower, 6.1m wide and 15m high, with walls 4.0m thick, mounting six cannon on a roof-top gun platform. The original entrance was high up on the south side and was reached by external wooden stairs. It was built on the site of an earlier blockhouse (probably dating from the mid-16th century), and would itself be modified during the 18th century, when a new gun platform was added, and the original entrance replaced by an entrance from the new gun platform. But following the Restoration, Scilly’s defences declined. In 1715, the engineer, Colonel Christian Lilly found the island’s defences in a poor state of repair and set about a series of improvements as part of a wider review of the defences of the south-west coast of England.

But Scilly’s worst military tragedy was only indirectly the result of war. In 1707 the British Mediterranean fleet, under Admiral Sir Cloudesley Shovell, was returning to England from an attack on the French port of Toulon. On 22nd October 1707, the fleet found itself in the treacherous waters off Scilly where six ships struck the Western Rocks and Association, Eagle, Romney and Firebrand were lost, and with them at least 1,450 sailors. Shovell’s body was washed ashore 8 miles away at Porthellick Cove on St. Mary’s where it was robbed of an emerald ring.

It was the War of Austrian Succession (1740-48) which brought about the next chapter in the story of the defence of Scilly. Under the guidance of Abraham Tovey, the Board of Ordnance’s representative on Scilly, a major programme of construction commenced. This focused principally on The Garrison where, over a period of seven years a line of stone ramparts was constructed along the coastline. Most of the circuit was provided with redans (two-sided angled positions protruding from the main ramparts) with only occasional batteries. The ramparts were built between 1741 and 1747 in five phases. There are distinct changes in construction with the regular smaller stones of the first phase giving way to larger blocks of stone. Another feature of the latter phases of construction were the sprouted drainage holes. Today, the walls of The Garrison make for an excellent coastal walk.

Whilst the defences were never put to the test, during the Napoleonic Wars they were rearmed, the size of the garrison was increased (the size of the local population was insufficient to provide an adequately sized local volunteer force, meaning that troops had to shipped in from the mainland), and, in 1804, a signal station was established on St. Martin’s (only to be moved to St. Mary’s the following decade). There were several naval actions in the waters surrounding the Scilly Islands, including, in 1796, the capture of the French 44-gun warship Virginie by HMS Indefatigable. Possibly coincidentally a former ECW redoubt on Toll’s Island, just off St. Mary’s east coast was rebuilt and named after Captain Edward Pellew.

More than 40 years after Waterloo, when in response to the growing strength of the French Navy, the 1860 Royal Commission on the Defence of the United Kingdom set in motion the construction of coastal defences which were to become known as Palmerston’s Follies, Scilly was excluded, to the extent that its own garrison was disbanded in 1863. Yet, developments and refinement of breech-loading guns in the latter years of the 19th century soon made the Palmerston forts obsolete. In response, in 1882, the Morley Committee investigated the defences of mercantile ports and recommended the creation of a series of defended ports including a protected anchorage for Scilly.

The plan was for two batteries each mounting a pair of the latest 6in. breech-loading guns (with a range of 11.5km) to be constructed facing south south-west, above the 18th century Woolpack Battery, on The Garrison. These would be supplemented by a pair of Defence Electric Lights (DEL), capable of illuminating enemy shipping in St. Mary’s Sound. As a defence against torpedo boats, two further batteries, each mounting a pair of 12-pounder Quick-Firing guns (with a range of 7.3km) were to be established, one facing west at Steval Point on The Garrison and the other facing north at Bant’s Carn, just over 2km north-east of The Garrison. In addition, there would be barracks, magazines, generators and control stations.

The scheme was approved in 1898 and construction seems to have been complete by 1905, a year after the Entente Cordiale brought to an end centuries of hostility with France. In 1906, the defences became virtually obsolete with the launching of HMS Dreadnought, and as a result, the defences were disarmed.

The U-boat threat

Less than a decade later, Scilly would find itself on the front line against a new foe and in a totally new form of warfare where the island’s location made them of strategic importance in this war against the U-boats. It wasn’t long before the Admiralty established a base for its anti-submarine patrols, with a flotilla of tugs and armed trawlers. An airship station was also proposed but this idea was soon abandoned and it was to be in another form of aerial warfare that Scilly would come to prominence.

MHM New Grimsby Seaplane Slipway (4)With the onset of unrestricted submarine warfare in 1917, the number of anti-submarine air-bases had to be increased. The location of Scilly meant that any aircraft operating from the islands would automatically increase the air-cover above the Western Approaches by nearly 50km. This led to the establishment of a sea-plane base at Porthmellon, just east of Hugh Town. But the warnings of the locals that this location was too exposed proved right and before the base was operational, it was moved to a new location at New Grimsby on Tresco.

The new base consisted of hangars, offices, stores and officers’ and ratings’ quarters, and a slipway which is still visible today. The base was initially equipped with Curtis ‘Large America’ flying boats and Short 184 seaplanes, and later, ‘Felixstowe’ flying boats. The base was operational in February 1917 and on 18th May 1917, a Scilly-based flying boat flew the first escort over a convoy. Less than a fortnight later, a ‘Large America’ spotted a surfaced U-boat near Bryher. In the subsequent attack, the flying boat was hit in the engine (a crew-member patched the damage with his handkerchief), but dropped 2 bombs and the U-boat was believed sunk. In August 1918, the unit became 234 Squadron RAF, and in all made 13 U-boat sightings and nine attacks.

In 1937, a civil aerodrome was established on St. Mary’s, but despite this air-link, Scilly was militarily underprepared when war came in September 1939. Civil preparations were well in hand, yet Scilly had just one company of soldiers, no anti-aircraft defence and hardly any naval presence. As a result of bombing raids in August 1940, Scilly’s garrison was increased to 1,000 troops and two 40mm Bofors anti-aircraft guns were installed.

MHM Star Castle (2)The raids continued into the next year, so on 19th May 1941, a flight of six Hawker Hurricanes from 87 Squadron was transferred to the aerodrome. Almost immediately, one of the Hurricanes was scrambled to intercept a German seaplane and 1449 Flight soon had its first kill. In just over a year, 1449 Flight would claim six enemy aircraft destroyed, two probable and two damaged and in 1942, the Luftwaffe declared a 90-mile daylight no-fly zone around the islands and so there were no further raids. But these successes were not without incident, however, as on 12th August 1943, one of the Scilly Hurricanes crashed into the masts of the Scillonian (the mainland ferry). This was one of several losses – another occurred in February 1944 when a Liberator crash-landed by the aerodrome, the skill and courage of the pilot saving the crew but tragically, not himself. Altogether, 23 servicemen lost their lives on or around Scilly during the Second World War, 16 of whom are buried in Old Town Churchyard.

In 1941, some 30 pillboxes were constructed around St. Mary’s coast, several cunningly camouflaged (such as the one built into the Woolpack Battery). From May that year, Motor Torpedo Boats were stationed in St. Mary’s Pool, which also became an RAF Air-Sea Rescue base and an emergency base for Coastal Command flying-boats. New Grimsby became a base for the small boats running agents in and out of France.

In 1944, first Scilly’s Hurricanes and then the garrison were withdrawn. Whilst the war continued around Scilly’s coasts for the remainder of the war (in June 1944, HMS Warwick was sunk by U-413, a merchant ship was torpedoed on 12th January 1945 and on 11th March, U-681 was sunk by a Liberator), the de-commissioning of Star Castle in December 1944 brought Scilly’s war to its close and in so doing, ended some 397 years of military activity throughout the islands.

There can be few other places anywhere in the UK which can match Scilly for the scope and depth of its military heritage and today, much of this is in the care of English Heritage (Star Castle, however, is in private hands and is a hotel). There are nearly 50 sites – two on the smaller islands, six on Tresco and 39 on St. Mary’s (14 of these on The Garrison). Finally, in Hugh Town, there is Scilly’s small but fascinating Isles of Scilly Museum, a fine starting point for any exploration of the Scilly Isles.



    • The museum is NOT closed. It has relocated into the Town Hall on St.Mary’s along with other sites around the Island. There is a very interesting museum trail as well.

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