The canal was conceived by Lieutenant-Colonel John Brown of the Royal Staff Corps of field engineers in 1804, during anti-invasion preparations, as a defensible barrier to ensure that a French force could not use the Romney Marsh as a bridgehead. It had previously been assumed that the marsh could be inundated in the event of an invasion, but Brown argued that this would take ten days to implement and would cause massive disruption in the event of a false alarm. At a meeting on 26 September 1804, the Prime Minister, William Pitt the Younger, and the Commander-in-Chief of the Forces, the Duke of York, both enthusiastically endorsed the scheme. John Rennie was appointed consultant engineer, and Pitt personally persuaded the local landowners to agree to the new canal. Construction was started at Seabrook, near Hythe in Kent on 30 October 1804. By May 1805 only six miles of the canal had been completed; William Pitt intervened and the contractors and Rennie were dismissed. The work was resumed by the Quartermaster-General’s department with Lt-Col. Brown in command. Civilian navvies dug the canal itself, while soldiers built the ramparts; up to 1,500 men were employed in the project. It was constructed in two sections: the longer section starts at Hythe and ends at Iden Lock inEast Sussex; the second, smaller section, runs from the foot of Winchelsea Hill to Cliff End. The two sections are linked by the River Rother and River Brede. Artillery batteries were generally located every, where the canal was staggered to create a salient, allowing the guns to enfilade the next stretch of water. A military road was built on the inland side of the canal, and crossings consisted of moveable wooden bridges. Any troops stationed or moving along the military road would have been protected by the earthen bank of the parapet, which was piled up with excavated soil. The canal was completed in April 1809 at a total cost of £234,000; it was hoped that tolls for use of the waterway and road would help to defray the cost. In addition to these works, a number of Martello towers were built to protect the vulnerable sluices that controlled the water level in the canal, being towers numbers 22 to 27 and 30, three of which are still standing.
Peacetime use
Despite the fact that the canal never saw military action, it was used to try to control smuggling from Romney Marsh. Guard houses were constructed at each bridge along its length. This met with limited success because of corrupt guards. Although a barge service was established from Hythe to Rye, the canal was abandoned in 1877 and leased to the Lords of the Level of Romney Marsh.
