A short History of the Nantes / Brest Canal
Each of the canal’s 236 locks is a considerable feat of engineering, built out of locally-quarried granite.In addition to helping boats to pass through the lock, the lock-keeper was responsible for controlling the flow of water in the canal.
The Nantes/Brest canal remains one of the most remarkable feats of engineering in Central Brittany, 150 years after its completion.
It starts life at the point where the river Erdre enters the Loire in Nantes and then follows a relatively flat course to Redon, where it crosses the Vilaine. From Redon it follows the route of the River Oust to Rohan, and from Rohan it crosses from the valley of the Oust to that of the Blavet, which it joins at Pontivy and follows to Gouarec. From Gouarec it follows the river Doré and begins its climb up to Glomel, the highest point on the canal (184 metres above sea level), and after passing through a cutting 4 km long and 25 m deep, it leaves the rivers which flow to the South and the East, and joins those that flow West towards the Rade de Brest. It descends along the river Kergoat, and then briefly joins the Hyère before following the meanderings of the river Aulne through Finistère past Carhaix, Châteauneuf-du-Faou and Châteaulin and then out into the sea at the maritime lock at Guily-Glas. From here boats were able to sail across the bay to Brest without difficulty.
Since the building of the hydroelectric dam at Guerlédan, in 1930, which flooded part of the canal and blocked traffic, it has not been possible to travel the whole length of the canal by boat, but in its heyday it took a horse-drawn barge twenty-five days to complete the journey from Nantes to Guily Glas. This meant travelling 360 km of canal and passing through 236 locks.
There is a common misconception that the canal was the brainchild of Napoleon Bonaparte, but this is an oversimplification of what actually took place: the idea of linking Nantes to Brest by an inland water-route was first put forward in the sixteenth century; various feasibility studies were carried out on the project over the ensuing centuries but the cost was always considered to be too high. The principal reason for building the canal was the recurrent warfare with Great Britain: British naval superiority allowed British ships to harass French merchant vessels as they sailed from Nantes to Brest. Successive administrations considered Brest to be of vital strategic importance, and in times of war the town often had to be supplied by transporting goods over the treacherous Breton roads –.which for much of the year were almost impassable. After the defeat at the battle of Trafalgar, Napoleon gave up contesting with Britain for control of the seas, and once again the problem arose of how to supply the city of Brest, which was now virtually besieged by the British navy. In the end, Napoleon gave the order to go ahead with the planned canal. Work began at a time when the French republic was suffering from shortages of every sort after years of warfare and revolution, and, inevitably, progress was slow. After Napoleon’s defeat in 1814, work on the canal ceased altogether.
The project was reinstated by the new regime, and work recommenced in 1822 as part of a plan for development and reconstruction.
In addition to the main aim of linking Nantes to Brest it was clearly the hope of the central government that the canal would bring a civilising influence to central Brittany, which was considered to be a particularly backward area of the country.
Although the canal was completed without major mishap and more or less according to the original plans, the project still ran seriously over budget, costing four times as much to build as had been originally estimated. Partly for this reason much of the subsidiary work was never completed – such as building roads to link villages to the canal and building quays along the route of the canal to facilitate local use.
In addition, by the time that the canal was completed, the long-standing enmity between France and the UK had abated and the countries had entered into a period of alliance, which has continued until the present time, meaning that there was no obligation for military supplies to be moved by inland waterways.
For most of its route the Nantes/Brest canal follows the course of existing rivers. The large number of locks involved in crossing from one river system to another slowed down traffic considerably. A horse-drawn barge could traverse a maximum of 25 locks in a single day.
Consequently, although the canal was busy at its two extremities, very little traffic plied along its whole course. An attempt to increase use of the canal was made in 1860 when it was dredged to give it a depth of 1.62 m along its whole length so that it could be navigated by boats of greater tonnage, but by that time the railways were in operation. Trains were able to carry larger loads at a much faster rate than the canal barges, and although the military authorities did use the canal to transport supplies for five years, they then cancelled the contracts.
The actual tonnage carried on the canal peaked just before the First World War, but during the war itself most of the horses used for towing, and even some of the boats, were requisitioned by the army and some were never returned.
The final blow to the canal came in 1930 when a hydroelectric company dammed the river at Guerledan and flooded the valley of the Blavet. Promises were made to build a series of locks so that boats could navigate round the dam, but the promises were never kept. The canal from Nantes to Josselin remained busy, but the section running through Central Brittany saw less and less traffic. Since 1957 the stretch from Guerlédan to Châteaulin has no longer been navigable.
In retrospect, the Nantes/Brest canal provides an early example of a grandiose, centrally-planned, engineering project reliant on outmoded technology, and therefore having no chance of success. At the same time as the first locks were being carefully constructed George Stephenson was opening the world’s first public railway, running from Stockton to Darlington, in the North of England.
Based on an article first published in the Central Brittany Journal July 2004 ©CBJ May 2004
