Mention roads that have become part of transport folklore and The Silk Road, Great North Road, Route 66 and the Trans America Highway will almost certainly get mention. It is unlikely that the N35 in rural eastern France will be included in this company.

Think of great transportation triumphs and the evacuation of Dunkerque and the Berlin Airlift come to mind. Again, the N35 is unlikely to be considered.

The N35 prior to The Great War was a quiet minor road winding through the countryside of eastern France. Today, it is a minor road, beginning at St Dizier and ending at its junction with the N3 trunk road some 9km east of Verdun.

Serving a largely rural community, it starts nowhere and ends nowhere but in 1922 its importance as a transport route was recognised when it was inaugurated as a National Monument by the French Government;

Voie Sacree.

The German assault on Verdun began on the 21^st February 1916. For 300 days and nights the bloodiest battle of The Great War was fought in the belief, on both sides, that if Verdun fell so would France. Defence of the Verdun salient was dependent on the constant supply of ammunition, provisions and men.

With the fortress town under attack from the north, east and south, the only supply lines were the normal gauge railway from Paris and the narrow gauge railway from Bar-le-Duc, some 70km south-west of Verdun and 20km north-east of the railhead at St Dizier. The mainline railway had been perfectly adequate in supplying the Verdun front since 1914 from the supply depot at Chalons-en-Champagne.

Within hours of the battle commencing the Paris line was broken in the Battle of Caures Wood. Once broken, the railhead at Bar-le-Duc became the sole supply depot, itself supplied from the railheads at St Dizier and Revigny. Bar-le-Duc was served only by the N35 and the narrow gauge 'Chemin de Fer Meusien'. This single track railway, named after the River Meuse and capable of transporting just 800 tons each day was never going to be sufficient if Verdun was to be defended.

As the threat of attack grew, a meeting had been held on 19^th February to determine the use of the N35 road, which ran almost parallel to the 'Meusien' between Bar-le-Duc and Verdun. The result was that on February 20^th the Commission Regulatrice Automobile (CRA) was formed at Bar-le-Duc to regulate and assure all transport to Verdun.

In charge of the operation was Captain Doumenc, who had previously organised the operation that became known as ‘The Taxis of the Marne’ when Paris taxis were used to carry troops to the Battle of the Marne in 1914. He had been handed a monumental challenge.

The lorries were still in the early years of development, yet to prove any sort of reliability and the road was a rural dirt road unable to withstand the weight of traffic without constant repair. During the time the route was running, weather from freezing heavy snow with the resultant thaw, which caused mechanical transport throughout the rest of the Western Front to be banned from the roads to protect them, to rain and the heat of summer that created stifling dust.

On February 20^th the first motor transport, mechanical transport in military parlance, groupings were requisitioned from St Dizier, Vitry-Le-Francois and Chalons-Sur-Marne. These comprised 3 and 2-ton American White lorries. On February 24^th the Collot reserve grouping, based at Beauvais was withdrawn from forestry work to assemble at Bar-le-Duc and on the 25^th the Parisse grouping brought the total to 175 motor sections. 3,900 motor lorries, 300 officers and 8,500 men were assembled at Bar-le-Duc. This total did not include vehicles of the 3^rd Army's 'Service Automobile' or the vehicles of the 2^nd Army R.F.V. (Region Fortifiee Verdun).

It was decided that the Meusien would carry all the food it could, whilst the mechanical transport would carry munitions, engineering materials, men and the surplus food from the Meusien. All the munitions were carried from Baudonvilliers railhead, near St Dizier and some 16km south of Bar-le-Duc from where the rest of the supplies were loaded. Troops arrived at Bar-le- Duc via the station at Baudonvilliers.

At midday on 22^nd February the first lorry set out from Bar-le-Duc on the start of what was to become an heroic feat of transportation.

The scale of the operation made it obvious that tight control and organisation was required. The road was restricted to traffic supplying Verdun, with all other traffic, including military, banned except for crossing points at minor roads. Known as 'The Route Gardee', or commonly just 'The Route', it was at the exclusive disposal of the Commander-in-Chief (Direction de Arrierre). The name, Voire Sacree, wasn't coined until after the war by writer and politician Maurice Barres.

The 70kms of The Route between Bar-le-Duc and Verdun was divided into 6 sections, or cantons. Canton 1 was essentially the loading yards at Bar-le-Duc with Canton 2 beginning on the town's outskirts. The Chef de Canton was responsible for controlling and maintaining the flow in his section. A written report was required to be sent to the CRA every day.

To assist, he had 1 officer, 2-4 NCOs and 10-20 guides or pilots. The number of pilots was determined by the number of posts placed along the canton. The number of posts being determined by the terrain and number of side roads crossing The Route in each particular canton.

The side roads were constantly used by horse drawn transport and foot soldiers as well as the local population. It is important to remember that amongst all the turmoil of the Western Front, civilian life was continuing as normally as possible. Keeping the side roads flowing freely, and without delays while crossing The Route, was as important as The Route itself.

The pilots, usually with motorcycles but sometimes small cars, controlled the speed of the convoy to allow traffic to cross The Route or negotiate stricken vehicles and road damage. By controlling the speed, the flow was maintained without ever stopping. This is possibly the first time that the concept of the rolling roadblock was used to create road space and time to clear obstacles.

Officers, naturally with larger touring cars than the pilots, patrolled ceaselessly to detect and deal with any problem before it could create the gridlock that would have been inevitable with the volume of traffic.

A telephone system was installed to allow communication between the cantons. This allowed the Chef de Canton to alert neighbouring cantons of any problems in his section. Trained telephoned operators manned the phones constantly and used standardised phrases to help avoid confusion. Each call would start with the canton identifying itself and then the canton it was calling. All the cantons would monitor the communication and record it, but only the canton called would reply.

This gave the opportunity to adjust the flow of traffic over a wider area and help ensure its continual running. Efficiently adjusting the flow was essential, not only when the inevitable breakdowns caused blockages but as the battle ebbed and flowed as all major battles do.

Each canton was responsible for the signage along its stretch. These signs were unique to The Route to prevent them being followed inadvertently by users of the side roads. The signs were made from boxes with one white canvas side with black inscriptions. At night, they were illuminated with candles inside the box. It was the Chef de Canton's responsibility to ensure there was sufficient signage and that they were obeyed. The signs identified The Route and warned of corners, gradients and the differing speed limits on particular sections.

The Chef de Canton was responsible for adherence to speed limits and spacing within his section. Speed limits were set at 15kph for lorries, 20kph for sanitary lorries and ambulances, and 30kph for touring cars.

During normal running the speed of the convoy, or 'noria', was below the 15kph maximum in order to reduce wear and tear on the lorries and, equally importantly, the road itself. However, in times of need as the battle intensified, speeds of up to 25kph were maintained. During these times of peak high speed running, some 50% of the lorries leaving Bar-le-Duc failed to reach Verdun and return without breaking down.

Lorries were not permitted to overtake the one in front, unless it had stopped. Touring cars, sanitary cars (although not sanitary lorries) and ambulances were permitted to overtake. This permission could be retracted by the Chef de Canton when road conditions dictated, either through obstruction, state of road surface or when The Route was running at full speed.

Every tenth lorry was fitted with a red disc to the rear and the following lorry was not permitted within 50 metres of it. This was to allow overtaking by cars and easier crossing of The Route by traffic on the side roads. It also made passing stricken vehicles and regulating the flow of the convoy by the pilots easier.

Drivers were strictly forbidden to stop for any reason other than breakdown or under direction from the pilots. If a lorry broke down and was not able to start again before the following one passed it, it was hitched to it and towed to a wider spot to be abandoned, simply pushed off the side of the road or towed to its destination. It was strictly forbidden for any other vehicle to stop to render assistance.

Any vehicle damaged beyond towing was cast to one side instantly to maintain the flow of traffic. Immediately a stricken lorry was mobile again, it rejoined the convoy.

Thirty mobile workshops constantly patrolled the length of The Route, repairing any stricken vehicle they found. Eight mobile tyre workshops replaced tyres torn from rims. Vehicles deemed too bad for repair at the roadside were recovered to one of the 'parcs' for overhaul.

The main parc was at Bar-le-Duc, which employed 14 officers and 1,430 mechanics and drivers. Those drivers were in addition to those employed driving the lorries on The Route. A parc was also established at Verdun, providing repair facilities at both ends of the Route. An additional overflow parc was established at Aulnay l'Aitre, near Chalons-en-Champage, employing 10 officers and 571 men. These were essentially repair and overhaul facilities and additional facilities existed at Troyes should they be needed. Both the parcs at Aulnay and Troyes were served by the railways.

All the efforts to ensure the efficient and constant running of the convoy would have counted for nothing if loading and unloading could not be facilitated speedily and efficiently and keep the convoy moving. Loading and unloading centres were set up at Bar-le-Duc and at Regret on the outskirts of Verdun.

The centre at Verdun was on a flat plain, now a modern industrial estate, outside the battle area. Transport from there to the front lines continued by horse waggon or light lorries. To have run the convoy into Verdun was deemed impossible as the narrow, war damaged streets would have created too much congestion. There was also the higher risk of fire and discovery by the Germans than in the countryside where camouflage was used to disguise the unloading centre.

The centres were built alongside the road and consisted of 3 yards with turning circles between them. Each yard was wide enough for 3 vehicles to be unloaded side by side and 400 metres long. The capacity of each yard was 40 lorries. The speed of unloading was such that as each lorry arrived at a yard, it was marshalled to the space left by a leaving one. At no time was The Route stopped while lorries waited to be unloaded.

Two thousand men were employed at the Verdun centre, working 8 hour shifts, 7 days a week. While they were filling one yard, another yard was being emptied by transport from the front. As each yard filled the convoy was directed to another yard and using this system the yards were constantly being filled and emptied in rotation. Immediately each lorry was emptied, it was turned around and returned to Bar-le-Duc empty or reloaded for return.

Returning lorries evacuated the workshops of the Meusien, engineering factories, the Verdun lorry parc and thousands of local inhabitants along with wounded or sick troops.

Normal traffic flow on The Route was 1,750 lorries per day in each direction, or one every 25 seconds. When the intensity of the battle increased, so did the flow of traffic and at times the traffic nearly doubled to one every 14 seconds.

However, those numbers only relate to the supply lorries. In addition, there were 800 ambulances, an undetermined number of sanitary lorries and 200 Paris buses carrying troops and fresh meat. At peak times, it is recorded that 4,000 vehicles in each direction filled The Route, requiring 300 officers and 8,500 men.

To combat deterioration of the road, 700,000 tons of limestone were used to constantly repair the surface. Quarried from as close to The Route as possible, 20 men per kilometre constantly threw broken stones under the wheels of passing traffic. The greatly reduced life of the tyres by using them to roll in the stones was considered the better option than causing restrictions with the use of road rollers. 10 cubic metres per kilometre per day were used. 16 lorries and 30 horse-drawn waggons were needed per 10 kilometres to maintain supply from quarry to The Route.

The Route was not only at risk from the heavy traffic. To protect it from German attack from the air, The Route was lined with anti-aircraft and machine gun posts. Seven Escadrille Americaine fighter squadrons using Nieuport 11 fighters were based at Vadelaincourt, alongside the N3 at its junction with the N35 and at Bar-le-Duc. These flew constantly along the length of The Route in a determined effort to keep the road protected from the air and flowing at all costs.

The Escadrille Americaine squadrons were largely made up of volunteer American pilots and were formed into the Lafayette Escadrille squadron in April 1916 with 38 American and 5 French pilots. Every day the railhead at St Dizier received 21 trains of food, 7 of ammunition, 9 of materials and 2 of troops for transfer to Bar-le-Duc and onwards to Verdun. Every day, on average 6 trains left St Dizier with casualties, all of whom had travelled back down The Route from Verdun.

Every day, in addition to that carried on the Meusien, 15,000 troops, 6,400 tons of materials and 1,500 tons of munitions were despatched from Bar-le-Duc. Every day 40,000 gallons of petrol, 4,500 gallons of oil and 2 tons of grease were consumed by the convoy with each lorry averaging 4mpg for the 135km round trip that took 18 hours.

Seventy of the ninety-five French Divisions that participated in the Battle travelled there via the Voie Sacree. They alighted from the lorries at Le Moulin Brule to continue on foot the nine kilometres to the front. A monument today marks the place they disembarked to continue on foot. The road is further commemorated with commemorative plaques in a layby at Erize la Brulee at the Bar-le-Duc end.

With both The Route and the Meusien running at full capacity and Verdun by no means secure, work began on a standard gauge railway between Nettancourt and Dugny. Started from both ends in March 1916, it was completed in June 1916 and was able to relieve the strain on The Route.

With the increase in motor lorries available in the Verdun area rising from just 31 in December 1915 to over 3,900, plus numerous service vehicles, by February 1916 it is inevitable that the initial Whites were joined by a variety of makes. Although Renault and Berliet were the most prolific, other makes included Aries, Barron-Vialle, Cottin et Desgouttes, Delaunay-Belleville, De Dion-Bouton, Buick, Latil, Luc Court, Packard, Panhard, Peugeot, Pierce Arrow, Rochet-Schneider and Vermorel.

There is the suggestion of British involvement. ASC archives, which provided most of the information, include handwritten notes regarding British fuel use in comparison to the French.

Fifty lorries are recorded as running 20 miles per day, qualified as 10 miles out and 10 miles back, and using 225/250 gallons of petrol, 20 gallons of oil and 28lbs of grease and averaging 4.5mpg. The journey itself is not recorded.

It might be that these are purely comparison figures, though it is curious that daily mileages are quoted and the number of lorries used. A simple note comparing French and British mpg figures would have sufficed if that was the only intent.

It is known that supplies were received at Bar-le-Duc through the railhead at Revigny. Coincidentally, the mileage quoted by the British is the distance between Revigny and Bar-le-Duc. Hopefully at some point in the future more information will be uncovered to confirm or deny British involvement in the defence of Verdun.

Military documents tend to focus on the event, in this case the road itself. There is little interest shown in the support network that allowed the event to happen. It is only possible to imagine the scale of the support network that enabled the Voie Sacree to operate.

The documents reveal that 700,000 tons of limestone were needed to keep the road in good repair. That does not suddenly appear, falling from the sky like rain. Every ton had to be quarried, transported to the road and scattered by shovel under the wheels of each passing lorry. Many hundreds of men must have worked in the quarries, each needing feeding and accommodation.

The quoted 20 men per kilometre shovelling stone onto the roads adds up to 1,400 men, probably working an 8 hour shift so in reality 4,200 men were needed. The 16 lorries and 30 horse drawn wagons needed between quarry and 10km of road quickly amount to 120 lorries and 210 wagons in addition to those on the Route. That is an additional 322 men, who if working 8 hour shifts quickly become 966. These all needed fuel, whether food, petrol or fodder, which had to be taken along the Route, probably to be dropped off at the villages along the Route for replenishing the men and lorries.

Consider the petrol. 40,000 gallons is just a figure, but consider every lorry had the petrol tank in the cab. The tank needed refilling using 2-gallon petrol cans. That is 20,000 petrol cans manually lifted into lorry cabs. How many oil cans are needed to pour 4,500 gallons of oil into engines?  Presumably it was the responsibility of the driver, in which case it is likely each driver only travelled one way in each shift, before refuelling and handing his vehicle to the next driver. That system requires accommodation for thousands of beds at each end of the Route.

It is inconceivable that the drivers were expected to complete a return trip of 18 hours, or that the lorries could complete the round trip without replenishing the fluids. Remember that drivers were regarded as skilled men and in short supply, so unlike Labour Companies and Infantry they tended to be regarded as less expendable. There would also have been the consideration that the Route must be kept running and the risk of drivers falling asleep and having accidents that could stop the road was not a viable risk.

The only official recognition of the ancillary services is that it employed at least as many lorries and personnel as the Route itself.

It is too easy to simply say that without the Voie Sacree then Verdun would have fallen. Statistics give an indication as to the scale of the operation, without providing any real comprehension. An interim report, translated from the French by the War Office provides perhaps the most vivid indication of the scale and particularly the speed and which the French organised and began the operation. From February 22^nd, when the first lorry ran along the Voie Sacree for the next 15 days we get an idea of the magnitude of the achievement.

The ammunition lorries covered 1,200,000kms, far enough to encircle the globe 30 times. In doing so they carried 3,000,000 tonnes of ammunition. This was at the cost of 1,200,000Fr Frcs, or, £42,857, which equates to £3,543,944 in 2017. Every tonne of ammunition delivered to the battlefield had incurred a transport cost of 50Fr Frcs equating to £1.79 or £148 in 2017.

Troop carrying lorries covered 800,000kms loaded and 900,000kms empty while carrying 15,000 men to strengthen the French defences. This cost 1,700,000Fr Frcs, £60,714 which equates to £5,020,580 in 2017. It cost more to take each man into battle along The Route than by First Class Rail.

The report explains that ‘miscellaneous’ transport is not included in the figures. This accounted for food supplies, sanitary supplies, engineering material, evacuation of the Meusien Workshops, engineering works at the parc at Verdun, men going on leave or the wounded, evacuation of the local population and all the other paraphernalia that a battle front requires.

Throughout the 10 months of the Battle for Verdun, traffic on the N35 never stopped, although the most important time was the five months between the opening of the battle and the completion of the main-line railway in June.