When Brest was blockaded by the English fleet, Napoleon decided to build the canal to provide a safe inland link between the two largest military ports of the French Atlantic front.

The canal was closed as a through route in 1920, when a section was submerged by Guerlédan dam (PK 227), a short distance west of the junction with the canalised river Blavet at Pontivy.

At the same time, the disappearance of all commercial traffic (in 26m long barges carrying up to 140 tonnes) resulted in the gradual silting up of the canal section between Rohan and Pontivy.

This use is not simply day rides, but an ever increasing number of people on cycling holidays frequently taking in the whole Nantes-Brest section.

The effect of this increase in tourism has been profound for central Brittany, and an area less known for tourism than the Brittany coast has had an influx of cyclists with the result that towns and villages on or near the canal have seen a welcome increase in income, number of shops, restaurants, hotels and campsites after many years of slow decline.