Tilbury Fort, also known historically as the Thermitage Bulwark and the West Tilbury Blockhouse, is an artillery fort on the north bank of the River Thames in England. The earliest version of the fort, comprising a small blockhouse with artillery covering the river, was constructed by King Henry VIII to protect London against attack from France as part of his Device programme. It was reinforced during the 1588 Spanish Armada invasion scare, after which it was reinforced with earthwork bastion, and Parliamentary forces used it to help secure the capital during the English Civil War of the 1640s. Following naval raids during the Anglo-Dutch Wars, the fort was enlarged by Sir Bernard de Gomme from 1670 onwards to form a star-shaped defensive work, with angular bastions, water-filled moats and two lines of guns facing onto the river.
In addition to protecting the Thames, in the 18th century Tilbury also began to be used as a transit depot and for storing gunpowder. It continued to be essential for the defence of the capital and a new artillery battery was added in the south-east corner during the Napoleonic Wars. The fort became decreasingly significant as a defensive structure as military technology developed in the 19th century. It was redeveloped to hold heavy artillery after 1868, providing a second line of defence along the river, but further changes in technology meant that it had become obsolete by the end of the century. Instead Tilbury became a strategic depot, forming a logistical hub for storing and moving troops and materiel throughout the First World War. The fort had only a limited role in the Second World War and was demobilised in 1950.
Tilbury Fort is now operated by the charity English Heritage Trust as a tourist attraction, receiving 16,154 visitors in 2014. Many of the more modern military features were demolished during the 1950s, with further restoration work taking place during the 1970s ahead of the site opening to the public in 1983. The 17th-century defences are considered by the historian Paul Pattison to be the "best surviving example of their kind in Britain", and the fort includes the only surviving early 18th century gunpowder magazines in Britain.
History
16th century
The first permanent fortification at Tilbury in Essex was built as a consequence of international tensions between England, France and the Holy Roman Empire in the final years of the reign of King Henry VIII. Traditionally the Crown had left coastal defences to the local lords and communities, only taking a modest role in building and maintaining fortifications, and while France and the Empire remained in conflict with one another, maritime raids were common but an actual invasion of England seemed unlikely.; Basic defences, based around simple blockhouses and towers, existed in the south-west and along the Sussex coast, with a few more impressive works in the north of England, but in general the fortifications were very limited in scale.
In 1533, Henry broke with Pope Paul III in order to annul the long-standing marriage to his wife, Catherine of Aragon, and remarry. Catherine was the aunt of Charles V, the Holy Roman Emperor, and he took the annulment as a personal insult.; This resulted in France and the Empire declaring an alliance against Henry in 1538, and the Pope encouraging the two countries to attack England.; An invasion of England appeared certain.; In response, Henry issued an order, called a "device", in 1539, giving instructions for the "defence of the realm in time of invasion" and the construction of forts along the English coastline.;
The River Thames was strategically important, as the city of London and the newly constructed royal dockyards of Deptford and Woolwich were vulnerable to seaborne attacks arriving up the estuary, which was a major maritime route, carrying 80 per cent of England's exports.; At the mouth of the estuary, the Thames narrowed considerably, forming a natural hub for communications: the "Long Ferry" took passengers into the capital, and the "Cross Ferry" moved traffic across the river.; ; This was also the first point that an invasion force would be able to easily disembark along the Thames, as before this point the mudflats along the sides of the estuary would have made landings difficult. Temporary defences had been constructed at Tilbury as early as the 14th and 15th centuries, although little is known about their design.
Under the King's new programme of work, the Thames was protected with a mutually reinforcing network of blockhouses at Gravesend, Milton, and Higham on the south side of the river, and West and East Tilbury on the opposite bank. West Tilbury Blockhouse, part of the inner line, was initially called the "Thermitage Bulwark", because it was on the site of a hermitage dissolved by the King in 1536.; It was designed by James Nedeham and Christopher Morice, supported by three overseers; prior to the work, the estimated cost had been given as £211, allowing for stone, timber, 150,000 bricks and of chalk.; ; The D-shaped blockhouse was curved at the front, with two storeys of gun-ports, and probably had additional gun platforms stretching along the river on either side of it; ancillary buildings were placed at the rear and the whole site was protected by a rampart and a ditch, with extensive marshlands and creeks giving additional protection to the east.; It was initially commanded by Captain Francis Grant and his deputy, and garrisoned with a porter, two soldiers and four gunners, equipped with up to five artillery pieces including a demi-cannon and sakers.; ;
The invasion threat passed and in 1553 all of the blockhouses were ordered to return their guns; Milton and Higham were demolished. In the summer of 1588, however, there was a fresh threat of invasion by the Spanish Armada. An army was mobilised to protect the mouth of the estuary and emergency improvements to the fortifications at Tilbury Blockhouse were made by Robert Dudley, the Earl of Leicester.; Queen Elizabeth I visited the fort by barge on 8 August 1588 and rode in procession to the nearby army camp, where she gave a speech to the assembled forces.; Fears of invasion continued even after the defeat of the Armada, and over the course of the next year the Italian engineer, Federigo Giambelli, reinforced the blockhouse with probably two concentric earthwork ramparts, with ditches and a palisade.; ; A boom was stretched across the river to Gravesend at a cost of £305.
17th century
In the early 1600s, England was at peace with France and Spain and as a result the coastal defences received little attention; surveys reported multiple problems with Tilbury Fort including flooding caused by the estuary tides, and ferry passengers and animals making their way uninvited into the fort.; ; In 1642 civil war broke out between the supporters of King Charles I and those of Parliament. Tilbury was controlled by Parliament, who placed the Tilbury and Gravesend forts under the command of a military governor, using them to control traffic entering London and to search for spies; it saw no military action during the war.; Tilbury remained in use during the interregnum, having a garrison of three officers and sixty-six men in 1651.
After Charles II was restored to the throne in 1660, he began a wide-ranging programme of work on the coastal defences. The Dutch fleet then attacked up the Thames in June 1667, but were deterred from going further for fear of the Tilbury and Gravesend fortifications. In reality, the forts were poorly prepared to resist a Dutch attack; at Tilbury there were only two guns ready for action. The Dutch struck the English fleet at Medway instead, giving enough time for the government to improve the defences along the Thames and mount 80 guns on the forts. In the wake of the conflict, the King instructed his Chief Engineer, a Dutchman called Sir Bernard de Gomme, to develop Tilbury Fort's defences further.
De Gomme prepared several plans for the King in 1665; a further iteration of the designs was submitted in 1670 and given royal approval.; Work began the same year but it took until 1685 to complete the project. The work was carried out by skilled contractors, who were supplemented by large teams of pressed men brought in from across the region; during 1671, up to 256 workers were employed on the site. Around 3,000 timber piles had to be brought from Norway for the project in 1671 to support the foundations in the marshy ground. The resources needed for the King's multiple defence projects became stretched, and one of the planned bastions at Tilbury, originally planned to face the river, was cancelled in 1681, in part to save money. The total cost of the project is unknown, but was significantly more than the original estimate of £47,000.
The result was a large, five-sided, star-shaped fort with four angular bastions, revetted in brick, with an outer curtain of defences, including two moats and a redoubt; two new gatehouses defended the entrance from the north.; Two gun lines of gun platforms, facing the river, stretched alongside either the side of the fort. The Henrician blockhouse was incorporated into the defences, but the Elizabethan earthworks were destroyed. The interior of the fort was raised up above the level of the marshes to prevent flooding, and barracks and other buildings were constructed inside.; The writer John Evelyn praised the new fort as "a Royal work indeede". Further work after 1694 replaced the wooden gun platforms alongside the river with more durable stone equivalents.
18th–19th centuries
By the start of the 18th century, Tilbury Fort was one of the most powerful in Britain. The number of artillery guns varied; in 1715 there were 17 demi-cannon and 26 culverins mounted on the west gun platform, and 31 demi-cannons and one culverin on the east; the following year there were reported to be 161 guns in total at the fort, although 92 of these were in poor repair and inoperable.
In addition to its role in protecting the Thames, the fort had various military uses during the 18th century. From 1716 onwards, the Board of Ordnance began to use it as a gunpowder depot; there were safety restrictions on moving gunpowder in and out of the London docks, so Tilbury was used instead.; Two large magazines were built, able to hold 3,600 barrels of powder each, and the old blockhouse and other buildings were converted to act as further magazines.; Eventually the fort could hold more than 19,000 barrels of gunpowder. It was also used as a transit depot for soldiers and, after the Jacobite rising of 1745, as a prison to hold 268 Highlander prisoners of war. The Jacobite prisoners were kept in the gunpowder magazines and 45 died from typhus before they were sent on to London for trial.
The living conditions at the fort were poor. It was surrounded by marshes, with a poor road network, and the garrison had to survive on collected rainwater, in addition to water from a spring. Malaria was a problem; in 1873, of 103 soldiers at the fort, 34 were admitted to hospital with it. The Army Medical Report for 1874 said that "Tilbury Fort has long been regarded as unhealthy, and the troops as of late years have been removed every six months".