The Royal Military Canal was built between 1804 and 1807.
It was con-structed as a defence against Napoleon when it was feared that an invasion by the Imperial Army was imminent.
The Canal was designed as a series of measured staggers at 800 feet apart (within cannon range) to defend each section.
Hitler, too, had to take account of this formidable obstacle in planning his invasion of Britain.
The Canal runs from Seabrook in Kent to Pett Level in East Sussex.
