The reconversion

During the month of September 1918, a few tunnellers had an interesting reconversion in practising bridge construction at Rosel in Normandy[1]. This group of men had already erected a bridge during the Battle of Cambrai, in November 1917, on the Bapaume-Cambrai road[2]. General Little, Chief Engineer of the Third British Army, and General Harvey, Chief Engineer of the IVth Corps seemed very interested in the tunnellers during a visit to the Rosel camp. Their interest in the New Zealanders urged them to choose this unit for the erection of the Havrincourt bridge over the Canal du Nord.

Begun in 1913, this canal was still under construction at the outbreak of the war. The Canal formed a kind of huge trench without water. In September 1918, it defined a front line between the British and the German Armies. A British offensive was under preparation by the end of September 1918[3]. If the attack would be a success, a bridge should have to be built to carry supplies, vehicles and also to allow the passage of reinforcements.

The construction site of the bridge was not easy, located at the crossing of the Canal du Nord by the Hermies-Havrincourt road. At this point, the tops of the smooth brick walled sides of the canal were separated by 180ft and were 100ft at their highest point. Bridges designed by the Royal Engineers covered a distance of 120ft maximum, not enough to link the two sides of the Canal[4]. The tunnellers would join two bridges together to form only one large construction. From an engineering point of view the task verged on the impossible.

On the morning on 27 September 1918, the First and Third British Armies attacked the German front line located near the Canal du Nord. The offensive was the starting signal for the New Zealanders to begin the erection of the bridge.

Havrincourt Bridge under construction

Photographed by Lieut. Robert H.P. Ronayne NZE

MS 2008/45, Auckland War Memorial Museum

The tunnellers feat

In order to optimize the performance, the whole force was divided into two shifts[5]. The first worked from dawn to midday and the second took over from then till dark. At 6am, the tunnellers began work on the skeleton of the bridge. The plan envisaged the erection of the bridge to the west side while two wooden towers would be constructed to pull and to carry the bridge over the canal to the east side.

The bridge structure was placed on slides which would guide the bridge over the canal. In four days, the structure was ready for the great manoeuvre. A counterweight of 20 tons built with rails was placed at the end of the bridge.[6]. The winches were installed on the two towers which could lift a total weight of 70 tons.

By 5pm on 1 October the launching operation began. Two days later, the structure was slowly slipping away from the other side of the canal. But the weight of the bridge tilted the frame slightly so that it was now 12ft below the level of the bank[7]. The two wooden towers had only served to pull the bridge over the canal, not to lift it.

The supreme part of the manoeuvre started. Any failure at this time would have spelt disaster. Both winches operated and slowly lifted the iron structure[8]. Inch by inch, the frame was closer to the level of the bank. Around 6pm, the bridge was lifted several inches above the ground level of the bank. The bridge was slowly pulled for the last time and linked both sides of the Canal. It was an amazing engineering feat for men who had never erected a bridge under such conditions.

The tunnellers on the Havrincourt bridge

Photographed by Henry Armytage Sanders

MS 2008/45, Auckland War Memorial Museum

Advance to Victory

Between the end of September 1918 and the Armistice, the fate of the New Zealand Engineers Tunnelling Company was confidentially connected to the movements of the infantry troops. The front line was not any more fixed. In seven weeks, it knew not only the most important backward movement of the conflict, but also the deepest[9]. All the Allied Armies, since the North Sea to the Meuse, were underway at the same moment, imposing a general eastward withdrawal to the enemy.

The Allies moved forward carefully while the work of the Royal Engineers was immense. The main communication axes were cut and must be quickly reconditioned: roads, railways and bridges. The Royal Engineers were snowed under with works. The Tunnelling Companies, as the New Zealand unit, brought a help more than welcome[10].

The New Zealand tunnellers were given a task of bridges erection which seemed not important. They were not at the front and were used on some miles behind the line in movement from Cambrai towards Maubeuge. Their works were nevertheless essential to pursue the movement of the troops forwards.

Bridges erected by the New Zealanders allowed to cross three main river obstacles: the Canal de l'Escaut which crossing Cambrai and linking the Canal de St-Quentin in the south, the Selle and the Ecaillon, two parallel rivers, separated by only two or three miles, to the southwest of Le Quesnoy[11]. Thus, the New Zealanders reconnected the communication roads and railways above natural obstacles at Noyelles-sur-Escaut, Masnières, Cambrai, Solesmes, Saint-Waast and Romeries.

Beyond their successful reconversion, the tunnellers worked with all members of the Royal Engineers to the reconnection of a split territory. Their task continued after the end of the hostilities on 11 November 1918.