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Plymouth Sound is a vast waterway fed by numerous rivers allowing access far inland. Such geography led it to become an important centre of trade from as early as the Iron Age. Later, as Britain's overseas interests led to development of a large navy, it became the country’s foremost military port prompting a myriad of defensive works throughout the ages.

The Royal Citadel, a fortification built by Charles II over the former Drake's Fort, occupies Plymouth Hoe.





Plymouth Sound has been a hub a maritime activity for thousands of years. The Rivers Lynher, Plymn and Tamar all flow into the Sound and provide access far inland enabling the settlements that grew up along their banks to have easy access to the sea. No later than the late Iron Age, the communities in and around the Sound were engaged in thriving international trade. Furthermore, from the seventeenth century onwards the Sound became a key base for the Royal Navy. With such a long and important history, Plymouth Sound has been the recipient of many fortifications over the centuries.


Early Defences: Iron Age and Romans

The early fortifications were promontory forts at Mount Batten (left) and Rame Head (right). Later a Roman-era settlement was established at Stonehouse.

There have been substantial settlements in the Plymouth region since at least the Bronze Age. Recent discovery of a settlement at Sherford, to the east of Plymouth, is probably indicative of wider settlement across the lowland areas of the region.  However, within Plymouth Sound,occupation seems to have gravitated around the headlands and these sites would have been fortified. Certainly an Iron Age fort was established on Rame Head and it is likely Mount Batten was also fortified as, no later than the first century BC, that site was being used as a major international port for trading with Mediterranean merchants. Local tin and copper would have been in high demand from continental customers and it is likely that South West Britain, quite probably through Mount Batten, was also a major exporter of corn, cattle, gold and silver. Given such trade, it would seem surprising if there were no fortifications.


The Romans invaded Britain in AD 43 and, whilst the key motivation behind that was probably political, the mineral exports of South West England undoubtedly provided the economic rationale. Accordingly the Second Augustan Legion (Legio II Augusta) was tasked with suppression of the area and they established a Legionary base at Exeter with outlying forts beyond. There is no evidence of a shore-based military presence in the Sound with the nearest known fort at Calstock, some fifteen miles further north along the line of the River Tamar. However, ships of the British Roman Navy (Classis Britannica) would inevitably have used the Sound as they proceeded inland to supply the fort and conduct other operations.  However, given the area's existing trade with the continent, it is probable the residents of the South West did not oppose the Romans and accordingly the military presence in the area was light. Roman era settlements and facilities were established at Mount Batten, Turnchapel and Stonehouse but it is unlikely any of these were fortified.


Medieval Defences

The earliest medieval fortifications around Plymouth were centred around the largest settlements - St Germans (Trematon Castle - right) and Plympton (Plympton Castle). In addition the fording point between Devon and Cornwall was also the site of a castle (Launceston Castle). Plymouth Castle (left) was added in the late fourteenth century.

By the arrival of the Normans in the late 1060s, Plymouth was a small fishing village called Sutton and was situated in the immediate vicinity of a natural harbour called Sutton Pool. The major settlements in the region were St Germans, Launceston and Plympton. St Germans, on the River Lynher,  was the largest and was a major Saxon port which also had a cathedral. As soon as they gained control of the area, the Normans built Trematon Castle to control movement along the Lynher estuary between St Germans and the Sound as well as to control the overland route to the town via the ferry at Saltash. To the north, on the banks of the River Tamar, was Launceston which was the centre of tin and copper mining as well as being the southernmost fording point into Cornwall and was also a recipient of a castle (Launceston Castle). Finally Plympton, just off the River Plym, was also a substantial settlement and a motte-and-bailey castle (Plympton Castle) had been built there no later than 1100.


The silting up of the River Plym coupled with the development of increasingly larger merchant ships, saw Sutton (Plymouth) grow at the expense of Plympton. Nevertheless the natural harbour, which offered easy access to the open sea, meant it grew in size and, by the time the Hundred Years War commenced in 1337, it was a thriving port. Unfortunately this also attracted unwanted attention leading to attacks by French and continental forces in 1340, 1377, 1400 and 1403 which prompted the construction of Plymouth Castle. Consisting of four towers it controlled a chain that barred access into Sutton Pool (similar arrangements existed at Dartmouth and Fowey) whilst early artillery pieces were installed within. In addition to the castle - and perhaps as a fore-runner to it - earthwork artillery batteries may have been established near the water at either the Hoe and/or Mount Batten. To protect the growing settlement, Plymouth's town walls were started around this time although how much work was completed is unclear as a map dated 1540 shows the circuit as incomplete whilst Robert Adams made a report to the privy council in 1592 recommending the construction of a modern and effective wall to provide protection to the town. The town walls did form a complete circuit by 1643.


Tudor Defences

The Tudor era saw artillery blockhouses being built at the entry points into the Hamoaze, Cattewatter, Sutton Pool and Millbay. A battery was also built to protect a water point at Bovisand Bay. Forts were established on Drake's Island and Plymouth Hoe.

The development of Stonehouse into a substantial settlement led to the construction of fortifications to control access into the Hamoaze and Millbay. These defences took the form of small artillery blockhouses and were constructed at Mount Edgcumbe, Devil’s Point, Firestone Bay, Millbay West and Millbay East. A further blockhouse, protecting Sutton Pool and the entrance into Cattewater, was constructed at Fisher's Nose around the same time. These were privately funded initiatives by Sir Richard Edgcumbe, owner of Stonehouse and who had vested interests to protect. These relatively new structures, along with the presence of Plymouth Castle, meant the Sound did not receive a 'Device' fort during Henry VIII's great coastal defence programme of 1539-45.


Further fortifications were also built during the Tudor period. In 1551 St. Nicholas' (later Drake's) Island, which had long been in use by the Crown as a customs facility, was fortified at Crown expense. Plymouth increasingly hosted large numbers of privateers and naval ships and, upon the outbreak of war between England and Spain in 1588, Sir Francis Drake sailed from the town to defeat the first great Armada (although not before finishing his game of bowls). Later, Sir Francis Drake pushed for further fortifications to protect Plymouth Sound leading to the construction of Drake's Fort in 1596. This was predominantly an earth and timber structure and took an unusual configuration due to the terrain of the Hoe and also due to its incorporation of the earlier Blockhouse at Fisher's Nose. A small artillery battery was also built on Staddon Heights, overlooking Bovisand Bay, to protect a small anchorage adjacent to a fresh water stream.


Civil War

The civil war saw Plymouth besieged by Royalist forces. Earthwork forts, similar to the Queen's Sconce (left), were built to keep the attackers out of artillery range of the town. To the south the Royalists held Mount Batten and Mount Edgcumbe but Parliament kept control of Drake's Island (right).

Plymouth, whose mercantile community had opposed Charles I's levy of Ship Tax during his 'personal rule / Eleven Years' Tyranny', supported Parliament when the Civil War started in Autumn 1642. Royalist forces sought to secure the South West of England for the King - Cornish tin was essential for funding the war effort whilst the area included ports enabling the import of men and war material from abroad. Sir Ralph Hopton was appointed as Royalist commander in the South West and initially sought to take Plymouth. His attack on the town failed as the residents had already augmented the medieval walls with several additional bastions - Resolution Fort (North East), Charles Fort (North Wall), St George (North West) and Franc Fort (South West). However Sir Ralph Hopton's subsequent victories at the battles of Braddock Down (19 January 1643), Stratton (16 May 1643), Lansdown (5 July 1643) and Roundway Down (13 July 1643) gave the Royalists a free hand. Plymouth now became a Parliamentary enclave and the medieval walls were no longer adequate as they would allow the attackers to get into artillery range of the ports at Sutton Pool and Millbay which were now essential for re-supplying the town. Accordingly an outer line of earthworks was constructed along the northern ridge running east/west from the old Stonehouse creek to Tothil. A series of earthwork artillery forts was added to this line - Newworke fort, Penycomquie Fort, Maudlyn fort, Holiwell Fort and Lipfot Fort. These forts have now been buried under modern developments but it is likely they took a similar form to the Queen's Sconce, a surviving Civil War earthwork near Newark in Nottinghamshire.


Throughout 1643 and 1644 the Royalists besieged Plymouth - and in one attack almost broke the defensive line when they briefly occupied Maudlyn fort. They also occupied Mount Edgcumbe, where a battery of cannons was installed, and established garrisons at Plympton and Saltash. After fierce fighting they also took Mount Batten effectively rendering the harbour within Sutton Pool untenable. Parliamentary forces did however sustain their control of Drake's Island. This was crucial as, with Sutton Pool out of use, Parliamentary ships needed to use Millbay to offload supplies. Even then they had to do so under the cover of darkness making covert runs in and out before dawn. A brief respite to the siege came in July 1644 when Royalists forces withdrew as Robert Devereux, Earl of Essex brought his Parliamentary army into the South West. However, the Earl's campaign ended in defeat at the Battle of Lostwithiel in September 1644 and Plymouth came under siege once more. Only in January 1646, as Sir Thomas Fairfax marched his army into the South West, did the Royalist threat to Plymouth finally recede. Ince Castle, a brick manor house nearby on the River Tamar, was built concurrent with the nearby carnage at Plymouth.

A map drawn by Wenceslaus Hollar in 1643 showing the earthwork forts and Royalist positions.

Dutch Wars

After the Civil War the country became embroiled in wars with the Dutch. The Commonwealth built Mount Batten tower during the 1650s whilst Charles II built the Royal Citadel in 1665.

After the Civil War the earthwork defences built to defend the town were demolished. However, peace did not last. With England bankrupt after years of war, Parliament attempted to rebuild the country's wealth by implementing the Navigation Acts. These imposed a monopoly on English colonies prohibiting them from trading with ships from any nation other than England. The Dutch, who relied upon trade with the colonies, declared war. To protect Sutton Pool, Mount Batten tower was built. This round artillery tower, when paired with Drake's Fort and Drake's Island, provided protection for the harbour. Periodic warfare continued with the Dutch after the Restoration leading to Charles II replacing the old Tudor era Drake's Fort with the Royal Citadel. This new structure, built directly over the former, was large enough to hold a substantial garrison and had artillery covering the harbour. Onlookers couldn’t help but notice that the Citadel also had extensive artillery facing towards Plymouth - perhaps indicative of a King who hadn't quite forgiven the town for the staunch Parliamentary support throughout the Civil War. Queen Anne's Battery was also established on the east side of Sutton harbour.


The Dutch Wars had another impact on Plymouth Sound. In June 1667 the Dutch had launched a daring raid on Chatham, then the primary base for the Royal Navy. Large swathes of the English Fleet was burnt and the flagship, the Royal Charles, was towed away. Accordingly the Government looked for a new harbour further away from Holland. This led to the development of Devonport, which was known as (Plymouth) Dock until 1824, into an important base for the Royal Navy. The plans were progressed during the reign of William III, ironically a Dutch Prince who had seized the English and Scottish thrones, with the construction of the first stone built naval dock in Britain.


Anglo-French Wars

Much of the eighteenth century was spent at war or with the threat of war looming large and accordingly investment was made in coastal defence centred around the entrance into the Hamoaze (left). However, Cawsand (right) was neglected and a Franco-Spanish fleet came close to achieving a successful landing there.

England spent much of the eighteenth and early nineteenth centuries either at war or in immediate anticipation of it. The wars of Spanish (1701-14) and Austrian (1740-8) successions, the Drummers War (1721-5), the Seven Years War (1756-63), the French support to the Jacobite Rebellions, the Carnatic Wars, the revolutionary wars of the 1790s and the Napoleonic wars (1803-15) - all of these ensured continued expenditure on both the Royal Navy and coastal defence. In particular defences focused on protection of the channel into the Hamoaze and River Tamer, on which the naval base was built. On the land side the Naval dockyard was surrounded by the Devonport Lines, stone and earthwork ramparts with large bastions (George's Bastion and Stoke Bastion) equipped with heavy guns and fronted by a shallow ditch. These works were completed no later than 1765 although were modified in the 1770s, 1780s and again in the early 1800s. Various redoubts protected the land approaches including Mount Pleasant, north of Millbay, and Bluff Battery whilst sea access was controlled by batteries at Mount Wise and at East and West King. Additional artillery defences were also established on Devil's Point, the western side of the Hoe and around the dockyard itself whilst the fortifications upon Drakes Island were also upgraded at this time.


Despite the extensive nature of the new defences, they were shown to be inadequate. In 1779 a Franco-Spanish fleet anchored in Cawsand Bay intending to land 30,000 soldiers ashore with the intention of seizing the Maker Heights and bombarding the dockyard from afar. Although frustrated by a storm, as well as the timely arrival of a flotilla of Royal Navy ships under Sir Charles Hardy, this prompted the construction of Amherst Battery to guard Cawsand beach. The Maker heights themselves were also extensively fortified with the construction of numerous redoubts to ensure control of the high ground.


Palmerston Forts

The launch of La Glorie in 1858 prompted the biggest peacetime military infrastructure programme in British history. Crownhill Fort (left) and Fort Staddon were both part of the new scheme.

By the mid-nineteenth century there had been peace with France for over thirty years. Whilst some expenditure had been made on coastal defence, including construction of East King Battery in 1844, on the whole the defences around the country had been neglected in favour of maintaining an enhanced naval fleet. Britain's defence policy relied upon the Royal Navy to protect both the homeland and the increasing number of colonies and possessions overseas. To ensure domination, the Royal Navy was maintained at a strength greater than the combined size of its two biggest competitors. However, in December 1851 Louis-Napoleon, President of France, declared himself Emperor Napoleon III. This prompted significant concern in England that there would be a resumption of the Anglo-French wars and accordingly coastal defence arrangements were again scrutinised. Staddon Point Battery was raised at this time.


Initial tensions between Napoleon III and Britain were eased when the two countries worked together during the Crimea War (1853-56). However, in 1858 the French launched the world's first seagoing Ironclad warship, 'La Gloire' (the Glory), starting an arms race with Britain. This armoured warship instantly rendered the wooden sailing ships of the Royal Navy obsolete and prompted fears of invasion. A Royal Commission was established to review coastal defence and that body recommended a vast fort building programme around Plymouth Sound to ensure the protection of the Royal Navy's dockyard at Devonport. Unlike previous eras - where defences had been situated around the Hoe and at the entrances to Sutton Pool, Millbay and Stonehouse harbours - development of long range artillery meant land defences needed to occupy the higher ground whilst the building of the breakwater (1811-48) meant the sea defences needed to be further south than before. Accordingly five distinct schemes were commissioned - the Northern Lines, Staddon Lines, Western Lines, Outer Sea Defences and Inner Sea Defences. The first three were focused on landward defence ensuring an enemy force did not circumvent the sea defences by moving inland around them in order to attack the dockyard from the rear. Dispensing with the bastions, a design that had held prominence since Tudor times, the forts were constructed on a polygonal design with the intent that they would act in unison to provide an unbroken wall of fire. The sea defences were focused on denying an enemy access into Plymouth Sound with the Outer Lines barring access through the breakwater and the Inner Defences denying access into the Hamoaze and River Tamar. Collectively the land and sea defences completely enclosed Plymouth Sound and the high ground surrounding the entire area thus ensuring the safety of the dockyard.


Political opponents labelled the forts as 'follies' due to the high cost and a deliberate misunderstanding of why the guns were 'facing the wrong way' on those forts protecting the land approaches. However, many of the Palmerston forts retained an active military role until the 1950s with Crownhill Fort continuing in that role until the 1980s whilst others - Fort Staddon, Scraesdon Fort and Tregantle Fort continue in use by the Ministry of Defence. The primary fortifications of each of the defensive lines were as follows:

Northern Lines

(Land Defences)

Staddon Lines

(Eastern Defences)

Western Lines

Outer Sea Defences

Inner Sea Defences

Artillery Developments


Whilst the fort building programme was ongoing during the 1860s and early 1870s, developments in artillery continued that were particularly relevant to the sea defences. Those forts tasked with defending against ships were built with their guns enclosed in armoured casemates designed to withstand an artillery exchange. These allowed the guns, the vast majority of which were muzzle loading, to be re-armed in safety but the downside was they were slow to fire and the casemates quickly filled with smoke that was difficult to extract. To overcome this, Moncrieff mountings were devised. Guns on this type of carriage could be installed in a pit, raised to be fired and then lowered for re-arming. Furthermore experiments were conducted with traditional muzzle loading weapons installed upon high angle mountings enabling them to be trained up to 70 degrees from horizontal and thus delivering plunging fire upon enemy ships. Again such guns could be installed in open barbette gun emplacements. However, it was ultimately the development and mass procurement of heavy breach loading weapons that made casemated forts obsolete. Such guns were ideal for open batteries and this effectively became the standard from the late 1880s onwards. As artillery ranges continued to improve, new coastal defence batteries were built around Plymouth Sound to extend the range of the guns out to sea. In the west new batteries were built at Tregantle (High Angle), Whitsand Bay, Rame Head and Maker Heights. In the east batteries were built at Lentney and Renney Point. An anti-ship torpedo site was also established at Piers Cellars and equipped with the latest Brennan Torpedo.


Although the primary armament of many of the original Victorian sea defence forts had been rendered obsolete, their low waterline position made them ideal for a new type of weapon system - the Quick Firing gun. These had been developed to counter the threat of Fast Motor Torpedo Boats and, during the 1890s, many of the existing forts were equipped with them including Fort Picklecombe, Garden Battery and Staddon Point Battery.

The open batteries of the late 1880s/1890s are perhaps best viewed at Whitsand Bay Battery. By the time these had been built, Plymouth Sound was one of the most heavily fortified sites in the country.

World Wars


Many of the sites of the earlier defences were re-utilised for one or both of the World Wars. Whilst the threat during the First World War was minimal, it became particularly important in 1940 when the South coast found itself as a frontline against German occupied France. As air attacks increased, ten heavy Anti-Aircraft Batteries were installed around Plymouth including at Bere Alston, Carkeel, Maker Heights, Plympton and Down Thomas. Barrage balloons were rigged at numerous locations including Staddon Heights and Devonport Park. To counter the E-boat (fast torpedo boats) threat, many of the Victorian defences were upgraded although the focus was installation of searchlights and quick firing guns. Mount Batten, Drake's Island, East and West King Batteries, Devil's Point, Fort Bovisand and Fort Picklecombe all had coastal defence batteries installed whilst anti-air batteries were placed in many of the Palmerston forts - their deep and large magazines making them ideally suited for this purpose. The Breakwater Fort was used as a lookout and signalling station and Mount Batten continued to be used as a seaplane station supporting RAF aircraft operating against U-boats in the Battle of Atlantic.



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