History of Dover Castle

Known as the ‘key to England’, the great fortress of Dover Castle has played a crucial role in the defence of the realm for over nine centuries, a span equalled only by the Tower of London and Windsor Castle.

Aerial view of Dover Castle showing the various phases of the hilltop site

The castle’s massive ramparts and ditches may have originated in an Iron Age hillfort. At the centre are the Roman lighthouse and Anglo-Saxon church, and above them are the great tower and inner bailey

Before the Castle

Commanding the shortest sea crossing between England and the continent, Dover Castle has a long and immensely eventful history. Many centuries before King Henry II began the great stone castle here in the 1180s, its spectacular site above the famous white cliffs may well have been the site of an Iron Age hillfort.

The Romans built a lighthouse – one of the best-preserved in Europe – on the heights here after they invaded in AD 43, to guide ships into the harbour. The Anglo-Saxon church beside the lighthouse was once probably part of a Saxon fortified settlement. Restored in the late 19th century by Sir George Gilbert Scott and William Butterfield, it is the largest and finest Saxon building in Kent.

Immediately after his victory at Hastings in 1066, William the Conqueror strengthened the defences with an earthwork and timber-stockaded castle. From then on Dover Castle was garrisoned uninterruptedly until 1958.

The recreated king's chamber on the second floor of the great tower at Dover, fitted out to evoke a late 12th-century royal palace

The recreated king’s chamber on the second floor of the great tower, fitted out to evoke a late 12th-century royal palace

The Medieval Castle

In the 1180s Henry II remodelled the castle, planning its great tower as a palace in which to entertain great visitors as well as a last redoubt for a strategically important castle. At 83 feet (25.3 metres) high, just under 100 feet (30 metres) square and with walls up to 21 feet (6.5 metres) thick, it has three floors of rooms, the topmost being state apartments for the king himself.

Within this magnificent showpiece, Henry could welcome and impress distinguished visitors to England – particularly noble pilgrims travelling to the new shrine in Canterbury Cathedral of Thomas Becket. The archbishop was slaughtered in front of the altar there by Henry’s household knights on 29 December 1170, ten years before the great tower was begun. On the second floor of the great tower is a chapel dedicated to Becket, with richly decorated stonework. 

Building work continued in the first half of the 13th century under King John and Henry III, who completed the successive rings of defensive walls surrounding the great tower.

Artist’s impression of the great siege of Dover Castle in 1216

An artist’s impression of the great siege of Dover Castle in 1216, showing French forces undermining the northern defences of the castle
© Historic England (illustration by Peter Dunn)

The Great Siege

In 1216–17 these defences were twice put to the test when Dover withstood a long siege by an invasion force led by Prince Louis of France in support of English barons rebelling against King John. The fortress resisted ten months of bombardment by siege engines, undermining by tunnels and eventually hand-to-hand fighting.

Following the siege, John’s son Henry III added three powerful new gatehouses and a fortified spur extension to the castle. By the 1250s the medieval defences had assumed the extent and shape they retain today, a highly visible symbol of English royal power.

View down passageway with cannon ranged left and right down its length

The upper level of the protected passage, or caponier, built as part of the outer defences to the north of the castle during the Napoleonic Wars

The Castle Transformed

After the Middle Ages Dover was continuously garrisoned into the 20th century. Although it declined in importance from the 16th century, it still hosted royal visits by Henry VIII, Elizabeth I and Charles I’s queen, Henrietta Maria.

From the 1740s onwards the medieval banks and ditches were reshaped as the castle was adapted for artillery warfare. Later in the 18th century, when England faced the threat of invasion from Napoleonic France, even more spectacular additions were made to the castle’s defences. To house the huge numbers of troops needed to man them, a network of tunnels was dug in from the cliff face for use as barracks.

The reconstructed coastal artillery operations room in the Second World War tunnels at Dover Castle

The reconstructed coastal artillery operations room in the Second World War tunnels at Dover Castle

Dover in Two World Wars

By 1905 advances in technology made it possible for coastal artillery around the harbour to be controlled from a central Fire Command Post built on the cliff edge. Its commanding position led the Admiralty to site a signal station on top of it in 1914, from which the Navy controlled the movement of all ships in and out of the harbour.

The Napoleonic tunnels were brought back into service in the Second World War, when they made their most notable contribution to British history. From 1939 they housed the command centre that controlled naval operations in the Channel. It was from here that in May 1940 Vice-Admiral Bertram Ramsay organised the extraordinary evacuation of British troops from Dunkirk.

Over the next few years the tunnels were greatly extended to serve as both a hospital and a large combined headquarters, responsible for guarding the Straits of Dover and involved in preparing for the 1944 invasion of Europe.

Later, during the Cold War, this network of tunnels was transformed into the secret location of one of Britain’s Regional Seats of Government, with the role of organising life in the event of a nuclear attack.

         

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