The Royal Military Canal stretches 28 miles from Cliff End at Pett to Seabrook at Hythe. This canal wasn’t created for trade however. It was built as a defensive line, a third line of defence against the expected invasion by Napoleon. Had he made an attempt to invade, he would first need to defeat the Royal Navy. That done the line of Martello Towers would next need to be overcome. If they made it past the towers, they would then face the Military Canal.
Started in 1804, it took 4.5 years to construct at a cost of about 19.5 million in today’s money. Napoleon was defeated at Trafalgar in 1805, which pretty much ended his ambitions of invading Britain. So the canal was obsolete by the time it was finished.
There is a break in the man made canal; at Winchelsea where it meets the River Brede and at Iden Lock where it meets the River Rother. The rivers take up the job of being the water barrier. It is the third largest defensive structure in the UK, after Hadrian’s Wall and Offa’s Dyke.
A good defensive structure never ages, so when Britain was again under threat of invasion, this time by the Germans, it was again used as part of a network of defences. Pill boxes were constructed along its length, some of which are still around.
The canal continues to serve an important function across Romney Marsh, acting as a source of water for irrigation during the summer and an outlet for flood water during the winter. It is also a haven for wildlife and fish as well as being very picturesque.