This unique military structure was built between 1804 and 1809 for strategic defence against invasion in the Napoleonic Wars with France (1793 - 1815)  It runs for 28 miles (45 kms) from Seabrook (near Folkestone) to Cliff End (near Hastings).

Why was the Canal Built?

In 1803, France declared war on England for the third time in ten years.  Being close to France, this part of the coast was threatened with invasion.


The reasons for the war between France and Britain went back more than 25 years and spanned two continents.

1776-1783  America declared independence and went to war with Britain.  France joined in on the American side.

1789  End of the American Revolutionary War.  Britain lost.  United States of America founded.

1789-1799  France, inspired by American Revolution, the population rose against the King.  The French Revolution began.  Napoleon Bonaparte took control of the French Army in 1796.

1796  Britain.  King George 111 and Parliament feared a revolution by the people.  Britain and other European countries started war against Napoleon in support of the French King.  Napoleon fought back successfully.  France became a Republic in 1799.

1802-3  After a short truce, Britain went to war again with Napoleon's France.  Napoleon threatened to invade Britain.

Defence of the Realm

Napoleon boasted:  "With three day's east wind I could repeat the exploits of William the Conqueror".

Napoleon planned to cross the Channel in fog with his Grande  Armée - 167,000 soldiers in 2340 flat-bottomed boats.  This plan was betrayed by an English spy, but the threat of invasion remained.

The Prime Minister of Britain at this time was William Pitt.  He promoted the idea of a strategic defence system.

A line of towers, forts and lookout posts was to be built all round the English coast from Suffolk to Sussex.  To protect the low shoreline of Romney Marsh, a fortified canal was planned.

This became the Royal Military Canal.  It was started in 1804.

The Canal was engineered by John Rennie (designer of London Bridge), directed by Lt Colonel John Brown, and built by soldiers and navvies ('navigators' - canal building workmen).

By August 1805 as many as 1600 people were working on the project.  Each navvy dug three cubic metres of earth a day.

Dual Purpose Design

The Canal had a series of forts and guardposts, and a unique cross-section to repel invaders.  Sharp 'kinks' every 600 yards (549 metres) could be defended by enfilade, or crossfire.

The Canal was expensive.  It cost £234,310 - the same as four of the biggest warships of the time.

Like modern military strategic defences it was also designed to provide civilian benefits.

Other uses for the Royal Military Canal

Commercial freight transport
Passenger boat services
Commercial stocked fishing
Management of water levels on Romney Marsh
Discouraging smuggling on this section of the coast

Built at last

The Canal took 22 months to dig.  But it was not ready for service until 1812.  By that time the French navy had been defeated at the Battle of Trafalgar (1805) and there was no longer any threat of invasion.

The Canal became part of the landscape and life of this part of Kent.

Today the Royal Military Canal is a unique monument to military and civilian ingenuity, to rank with such other important linear sites as Hadrian's Wall and Offa's Dyke.

The above information was copied from the Hythe Council information board next to the Canal in 2014.