The Battle of St Quentin Canal was a pivotal battle of World War I that began on 29 September 1918 and involved British, Australian and American forces operating as part of the British Fourth Army under the overall command of General Sir Henry Rawlinson. Further north, part of the British Third Army also supported the attack. South of the Fourth Army's 19 km (12 mi) front, the French First Army launched a coordinated attack on a 9.5 km (6 mi) front. The objective was to break through one of the most heavily defended stretches of the German Siegfriedstellung (Hindenburg Line), which in this sector used the St Quentin Canal as part of its defences. The assault achieved its objectives (though not according to the planned timetable), resulting in the first full breach of the Hindenburg Line, in the face of heavy German resistance. In concert with other attacks of the Grand Offensive along the length of the line, Allied success convinced the German high command that there was little hope of an ultimate German victory.
Background
Rawlinson wanted the Australian Corps, under the command of Lieutenant General Sir John Monash, with its well-earned reputation, to spearhead the attack. Monash was unhappy, because his Australian force was by now short of manpower, and many soldiers were showing signs of strain, having been heavily engaged in fighting for several months. There had been some episodes of mutiny by troops who were feeling unfairly put upon. Monash was however very pleased when Rawlinson offered him the American II Corps (the U.S. 27th and 30th Divisions), which still remained at the disposal of the British command, since American divisions were twice the numerical strength of their British counterparts. U.S. Corps commander Major General George Windle Read handed command of his American force for the duration of the action to Monash. However, the American soldiers lacked battle experience. A small group of 217 Australian officers and N.C.O.s was assigned to the U.S. troops for advice and liaison. The British high command considered that German morale was suffering badly and that their capacity to resist was much weakened. Monash believed that the operation would be "more a matter of engineering and organisation than of fighting." While there had been some evidence of poor German morale from previous operations, this proved to be a dangerous assumption.
Monash was tasked with drawing up the battle plan. He would use the Americans to breach the Hindenburg Line and the Australian 3rd and 5th Divisions to follow behind and then exploit the breakthrough. Monash intended to attack the Hindenburg Line south of Vendhuile where the St Quentin Canal runs underground for some 5,500 m (6,000 yd) through the Bellicourt Tunnel (which had been converted by the Germans into an integral part of the Hindenburg Line defensive system). The tunnel was the only location where tanks could cross the canal. Where the canal runs underground, the main Hindenburg Line trench system was sited to the west of the line of the canal. Two British corps, III and IX, would be deployed in support of the main assault. To Monash's plan Rawlinson made a very significant change: IX Corps would launch an assault directly across the deep canal cutting south of the Bellicourt Tunnel. This plan originated with Lieutenant-General Sir Walter Braithwaite, commander of IX Corps. Monash felt such an assault to be doomed to failure and would never have planned for it himself, believing it to be too risky. This view was shared by many in the 46th (North Midland) Division of IX Corps, which was tasked with spearheading the assault. The Germans believed the canal cutting to be impregnable.
Prelude
After the German spring offensive, British Empire, French, and American counterattacks during the Hundred Days Offensive brought the Allies back up against the outposts of the Hindenburg Line by the autumn of 1918, close to the village of Bellicourt, where the Battle of Épehy was fought on 18 September 1918.
Preliminary operation of 27 September
Monash's plan assumed that the Hindenburg outpost line would be in Allied hands by the date set for the start of the battle. While the Australians had already captured it in the southern part of the front (from where the American 30th Division would launch its attack), the northern section of the line was still in German hands. The American 27th Division was ordered to attack on 27 September, to finish clearing German forces from outposts in front of their line, including the strong points of The Knoll, Gillemont Farm, and Quennemont Farm. Commander in Chief Field Marshal Sir Douglas Haig initially opposed using the Americans to take the outpost line, wanting to preserve them for the main attack. He was persuaded by Rawlinson to change his mind. The British III Corps had previously failed to capture the outposts, but that failure had been attributed by Rawlinson to the tiredness of the troops. Rawlinson was convinced that the Germans were at breaking point and managed to persuade Haig that this was so. The American soldiers were inexperienced and problems were compounded by a shortage of American officers (there were only 18 officers in the 12 attacking companies whereas at the time a company would normally have roughly six officers each – the remainder were absent receiving further training).
The U.S. attack was unsuccessful. Monash asked Rawlinson for permission to delay the main attack due on 29 September, but this was refused because of the priority given to Marshal Ferdinand Foch's strategy of keeping the Germans under the relentless pressure of coordinated assaults along the front. As a result of the confusion created by the failed attack (with the corps command being unsure of where the American troops were), the battle on 29 September on the American 27th Division front had to be started without the customary (and highly effective) close artillery support. The British artillery commander argued that attempting to alter the barrage timetable at this late stage would cause problems, and the American divisional commander Major General John F. O'Ryan was also concerned about the possibility of friendly fire. All of the Allied commanders therefore agreed to proceed with the original artillery fire plan. The result was that the barrage would now start at the originally-intended jump-off point, some 900 m (1,000 yd) beyond the actual starting point of the infantry, leaving them very vulnerable during their initial advance. 27th Division was required to make an advance greater than any that had been asked of its highly experienced Australian allies, an advance of some 4,500 m (5,000 yd) in a single action. In an attempt to compensate for the lack of a creeping barrage Rawlinson provided additional tanks. However, the absence of a creeping barrage in the 27th Division sector was to have a very detrimental effect on the initial operations of the battle on the front opposite the tunnel.
Main assault of 29 September
The battle was preceded by the greatest British artillery bombardment of the war. Some 1,600 guns were deployed (1,044 field guns and 593 heavy guns and howitzers), firing almost 1,000,000 shells over a comparatively short period of time. Included in these were more than 30,000 mustard gas shells (the first use of a British-made version of this weapon). These were specifically targeted at headquarters and groups of batteries. Many of the high explosive shells fired had special fuses which made them very effective in destroying the German barbed wire. The British were greatly helped by the fact that they were in possession of highly detailed captured plans of the enemy defences (especially useful for the IX Corps sector). Monash's battle plan for 29 September envisaged breaking through the main Hindenburg Line defences, crossing the canal tunnel mound, breaching the fortified Le Catelet–Nauroy Line beyond that, and reaching the Beaurevoir Line (the final fortified line) beyond that as the objective on the first day. Monash had originally intended to capture the Beaurevoir Line on 29 September, but Rawlinson removed this as a first day objective, considering it overly ambitious.
Attack over Bellicourt Tunnel
On 29 September, the two American divisions attacked, followed by the two Australian divisions, with approximately 150 tanks of the 4th and 5th Tank Brigades of the British Tank Corps (including the newly trained American 301st Battalion, Tank Corps, which was equipped with British tanks) in support of the four divisions. The objective of the Americans was the Le Catelet-Nauroy Line, a defensive line east of the canal. Here the Australian 3rd Division (behind the U.S. 27th) and 5th Division (behind the U.S. 30th) were intended to "leapfrog" through the American forces and press on towards the Beaurevoir Line. Australian 2nd Division was in reserve.
On the left of the front, where the U.S. 27th Division began at a disadvantage, none of the objectives were met on the first day and the Americans suffered severe losses. The 107th Infantry Regiment suffered the worst casualties sustained in a single day by any U.S. regiment during the war. Rather than leapfrogging through the Americans, the Australian 3rd Division became involved in a desperate fight for positions that should already have been captured had Monash's plan run to timetable. Despite some individual acts of heroism the lack of progress on the left of the front had an adverse effect on the progress of the right of the front too. As the American 30th Division and then the Australian 5th Division moved forward whilst the units to their left did not, they had to contend with German fire from the side and rear as well as from ahead. An added difficulty was thick fog across the battlefield in the earlier stages of the attack which led to American troops passing by Germans without realising that they were there, with the Germans causing severe problems to the Americans following the assault wave. Fog also caused problems for infantry/tank cooperation. The 30th Division broke through the Hindenburg Line in the fog on 29 September 1918, entering Bellicourt, capturing the southern entrance of Bellicourt Tunnel and reaching the village of Nauroy, where Australian troops joined them to continue the attack.
The advancing Australians came across large groups of leaderless, disoriented Americans. Charles Bean wrote: "By 10 o'clock Monash's plan had gone to the winds.... From that hour onward ... the offensive was really directed by Australian battalion or company commanders at the front..." The 30th Division won the praise of General John J. Pershing, who wrote: "... the 30th Division did especially well. It broke through the Hindenburg Line on its entire front and took Bellicourt and part of Nauroy by noon of the 29th." There has since been considerable debate over the extent to which the American forces were successful. Monash wrote: "...in this battle they demonstrated their inexperience in war, and their ignorance of some of the elementary methods of fighting employed on the French front. For these shortcomings they paid a heavy price. Their sacrifices, nevertheless, contributed quite definitely to the partial success of the day's operations..." The objective of U.S. II Corps, the Catelet–Nauroy Line, was not captured by the Americans. During the battle, Monash was furious about the performance of the American divisions. Late on 29 September Rawlinson wrote: "The Americans appear to be in a state of hopeless confusion and will not, I fear, be able to function as a corps, so I am contemplating replacing them ... I fear their casualties have been heavy, but it is their own fault."
Meanwhile, on the right of the Bellicourt Tunnel front, the Australian 32nd Battalion under the command of Major Blair Wark established contact with the 1/4th Battalion, Leicestershire Regiment, of 46th Division, which had crossed the canal and were now present in force east of the Hindenburg Line.