Cambrai's significance as a transport hub is self-evident from this map. Its capture would cause chaos for the German army's logistic effort. The Cambrai battlefield is bounded by the St Quentin Canal to the east and Bourlon Ridge and Sensee River to the north. As the operation was conceived originally as a raid, these limitations on manoeuvre were intended to disrupt German counterattacks. Once Byng and Haig's ambitions for breakthrough entered the equation, they became a liability. Specific objectives (Blue, Brown and Red Lines) were only set for day one (1). Thereafter the planners envisaged a fluid battle of exploitation, with the Cavalry Corps sweeping through a narrow gap to wreak havoc beyond Cambrai (2) and infantry pressing onto Bourlon Ridge. The eventual aim was to consolidate on the Sensee River in order to threaten the entire Hindenburg system north of Cambrai (3). Subsidiary attacks west of the Canal du Nord would protect the flanks of the breach (4).
The opportunity for an offensive at Cambrai was established by Germany's retirement to the mighty Siegfried Stellung in February 1917. Since the failure of the August 1914 Schlieffen Plan, the German High Command (OHL) had opted for a defensive posture on the Western Front, concentrating instead on defeat of the Russians in the east. Nonetheless, an absolute refusal to accept any territorial withdrawal in the face of sustained Allied attacks through 1915 and 1916 had come at a high price. These extravagances on Verdun and the Somme cost them nearly 750,000 men. Infantry divisions were halved in size to disguise the damage but Germany could not match the Allies' stocks of manpower. The retirement they had resisted for so long became inevitable.
Originally conceived as an insurance policy, the Siegfried Stellung defensive system ran between Arras on the river Scarpe and the Chemin des Dames ridge above the river Aisne, saving 25 miles of front. In manning terms this equated to 13 divisions, precisely the number the Germans needed to create a viable theatre reserve. In the Cambrai area, these defences ran between the prominent obstacles of the St Quentin canal and uncompleted Canal du Nord, which was effectively a deep, dry ditch. Moving north, the line then cut abruptly north-west, across the Canal du Nord, in order to protect the vital rail hub at Cambrai and logistic conduit of the Sensee River. This created a bulge shaped like a nose, with the commanding Bourlon Ridge at its base. Salients always make tempting points to attack because they offer the opportunity to cut off enemy forces with only a modest penetration of their defences. The Cambrai area had added potential because it had not been fought over yet. Its gentle, chalk farmland was firm going and unscarred by shellfire.
This first attracted attention during the Allied spring offensives of April 1917 when the Commander-in-Chief of the British Expeditionary Force (BEF) , Field Marshal Sir Douglas Haig, suggested a combined Anglo-French attack on the tempting Cambrai sector. Lieutenant General Sir William Pulteney's IV Corps was instructed to submit a scheme but, by its completion, preparations for the summer Flanders offensive were well under way. Haig was still enthused by his Cambrai project but Flanders took precedence and General Headquarters (GHQ) shelved Pulteney's work.
Meanwhile, exponents of the tank were busy hatching schemes of their own. The tank's debut at Flers-Courcelette on the Somme in September 1916 had been premature. Though technologically cutting edge, the failing lay in application. In its conception, the tank was a 8 means of protecting infantry and thus it was employed, spread thin as 'an adjunct to infantry attack'. Unfortunately for its advocates, this emphasized the tank's shortcomings. In penny packets, mechanical unreliability had more impact. The tanks bogged down in the quagmire of old battlefields. Without doctrine and training, they failed to integrate with the infantry they were supporting. Despite evident potential, it was an inauspicious beginning.
The first step in rectifying this impasse was the creation of the Tank Corps on 27 July 1917. Hitherto, it had been part of the Machine Gun Corps as its 'Heavy Branch'. Now free to pursue their own doctrine, they were desperate to organize a bespoke operation. They knew that Flanders was the worst possible environment and would only exacerbate the scepticism of senior commanders and fighting infantrymen alike.
Colonel John Fuller (always known by his initials 'J. F. C.'), the now-famous interwar military thinker, was then Chief of Staff to BrigadierGeneral Hugh Elles, commander of the Tank Corps. He recommended a large-scale raid as the best showcase for their tanks. GHQ turned down an initial suggestion of Neuve Chapelle because of a lack of infantry to support it. Undeterred, Fuller settled on Cambrai as it carried the potential for French involvement, thus addressing the misgiving over lack of infantry. He too saw its favourable setting - perfect for a raid. Bounded by the St Quentin Canal, his proposed force of infantry, tanks, cavalry and aircraft could wreak havoc behind the German front line, whilst protected from counterattack by the canal obstacle.
Their plan secured the interest of Haig and his operations staff but was vetoed by the ever-practical Lieutenant-General Sir Lancelot Kiggell, the Chief of General Staff BEF, on the grounds that it would detract from the ongoing Flanders offensive. However, it also came to the attention of General Sir Julian Byng, recently promoted to command of Third Army off the back of a prodigious spell leading the Canadian Corps in First Army. Third Army had assumed responsibility for the Cambrai sector during June in order to free up forces for Flanders. An imaginative officer, Byng latched onto Fuller's ideas and directed his staff to start incorporating the legacy arrangements inherited from Pulteney.
Despite its convoluted conception, Byng and Elles were the chief architects of Operation GY. Even so, Haig was always in the background. Though he tried to keep a respectful distance from detailed planning, in practice his influence was significant. He controlled the tap on reserves and gave Byng just 48 hours to demonstrate that GY was going to achieve its objectives. After the costly obstinacy of Flanders, Haig was conscious not to push his infantry too far. Cambrai represented an opportunity; desirable but not essential to the effort on the Western Front.
In terms of both planning and execution, Cambrai reflects some of the enduring challenges of command in World War I. Of particular pertinence was the integration of emerging technology. It is a common temptation to criticize senior commanders of the period for failing to exploit technologies we now know to be pivotal. Tanks are an excellent example. Their dominance in modern warfare does not necessarily secure their relevance to the conduct of operations in 1917. Myopic as they often appear, commanders were under pressure to win a war. Inevitably, this involved the painful task of prioritizing industrial and military resources. As Paddy Griffith puts it in his study of battle tactics on the Western Front, it was always deemed preferable 'to take a longer but more certain path to victory ... than opt for some "death or glory" adventure which ran every chance of failure.' The fluidity of battle imbues all soldiers with a highly developed sense of practicality, placing stock in simplicity of plans, reliability of equipment and sustainability of effort.
Nevertheless, the primary constraint on exploitation of technology was not conceptual. It was the abject inability of commanders to influence events once operations were in progress. Telegraph, field telephones and motorized dispatch aided administration and formulation of planning but were redundant once troops crossed the start line. Thereafter, battlefield communications were little more advanced than in Napoleonic times: runner, bugle, flag, etc. At least the Napoleonic commander was able to survey his battlefield. Trench warfare was a nightmare - diffuse and yet slaved to interdependence with flanking units. By late 1917, the situation had been mitigated by novel solutions like the use of ground marker panels to signal passing aircraft. But these stopgap measures were not extensive enough to alleviate the imperative for prescriptive planning. Only by timetabling events and imposing pauses were commanders able to maintain a semblance of control. The consequence was a catalogue of exasperating lost opportunities.
NEC JACTANTIA NEC METU ("zonder woorden, zonder vrees")
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