This month is the 100th anniversary of Cambrai, which saw tanks fight alongside mounted soldiers for the first time in a turning point in the First World War.

For more on the Cavalry in the First World War, read their original letters in Cavalry in the First World War.

CAMBRAI

In July 1917, just before the Third Battle of Ypres, commonly called Passchendaele, Field Marshal Sir Douglas Haig, a cavalryman, told his army commanders on the Western Front that “opportunities for the employment of cavalry in masses are likely to offer”. Meanwhile, on the other side of No Man’s Land, the German chief of staff, General Erich Ludendorff, an infantryman, was convinced that “trench warfare offered no scope for cavalry”. Instead, he wanted to turn them into infantry and give their horses to the artillery and transport: “The wastage in horses was extraordinarily high and the import from neutral countries hardly worth the consideration.”

One of Ludendorff’s other problems was the shortage of corn and forage. Many parts of Germany were starving. The winter of 1916-17 became known as Kohlrübenwinter (“Turnip Winter”), when reibekuchen mit rübenkraut (potato cakes with sugarbeet syrup), still today a curious favourite of German Christmas markets, became a staple for many. The army fared little better at times and horses naturally took second place to the humans.

The shortages were due in large part to the Royal Navy’s blockade, exacerbated by the strange inability of the German authorities to regulate agricultural practice and prices. Farmers fed grain to their animals although its nutritional value as bread was four times that of grain eaten indirectly through meat. Prices incentivised farmers to slaughter stock rather than breed, so that there was a compounding shortage of animals and therefore manure. Smaller harvests resulted and more fertilizer had to be produced by industry at the expense of explosives.

Manoeuvring a Mark IV male supply tank over a trench.

Haig’s cavalry was on short rations, too. Because of interruptions to shipping, not least by U-boats in the Channel, the daily allowance had been cut from 12lb of oats and 12lb of hay to 9lb of oats and 6lb of hay. It was not restored until late April, when bran (not a great nutrient) and linseed was issued as a supplementary ration. One regiment, the 9th Lancers, fed thatch to its horses.

But while Ludendorff saw the Western Front as siege warfare on an industrial scale (materialschlacht), Haig, as a fellow general put it, regarded it as “mobile operations at the halt”. Having succeeded Sir John French (also a cavalryman) as commander-in-chief in December 1915, Haig constantly sought a return to the war of movement of 1914. Field Service Regulations – the Army’s “bible” – stated: “Decisive success in battle can be gained only by a vigorous offensive,” the chief factor in which was “a firmer determination in all ranks to conquer at any cost”.

In Haig’s view, this meant an offensive leading to breakthrough and then rapid exploitation, and cavalry was therefore of the first importance.

It was certainly true in August 1914, when a million Germans were wheeling through neutral Belgium to envelope the French army. The British Expeditionary Force (BEF), around 80,000 men, had found itself in the eye of the storm and its single cavalry division played a key role in preventing the Germans from outflanking the infantry during its 10-day retreat towards Paris and then in the so-called “Race for the Sea”. However, despite reinforcements, pouring into France from Britain and the outposts of Empire (regulars, reservists, territorials and the Indian Army, including cavalry) by December stalemate had developed, with trenches running continuously from the North Sea to the Swiss border. The cavalry on both sides found themselves unemployed, unless dismounted.

Tank trains at Plateau Station – on top are brushwood “fascines” to be dropped into trenches so tanks could cross.

Both sides tried to break through in 1915, but without success. Their cavalry was left champing at the bit in frustration. It was the same again in 1916: first the Germans at Verdun and then the British and French on the Somme. Fortunately, away from the front, minds had been at work on the problem of how to penetrate the German lines. In February 1915, Winston Churchill, First Lord of the Admiralty (Navy minister), had set up the Admiralty Landships Committee to investigate the potential of a tracked device that could crush barbed wire, cross trenches and bring fire to bear on the enemy from behind steel protection. The development work was done by William Foster & Co Ltd of Lincoln, specialists in agricultural machinery. In September 1915, Fosters tested a first design, little more than an armoured box on American tractor caterpillar-tracks, but it could not cross a gap of 5ft – the average trench width – for the tracks were prone to shed. By December, the company had produced a completely new design with bigger tracks wrapped round a hull with forward-sloping “prows” projecting beyond the crew compartment – a rhomboid giving the machine huge reach. On 20 January 1916, sheathed in tarpaulins, the 28-ton “tank”, a deliberately vague term alluding to its boxy shape, was taken to Burton Park outside Lincoln and put through its paces. It crossed a trench 8ft wide, climbed a 5ft parapet and crushed barbed-wire entanglements at a steady walking speed of 4mph.

A week later the “tank” was on its way by rail to Hatfield Park in Hertfordshire for demonstrations to the War Office. Field Marshal Lord Kitchener, Secretary of State for War, thought it “a pretty mechanical toy but without serious military value”. Fortunately, Major-General Richard Butler, an infantryman and Haig’s deputy chief of staff, saw its potential and asked simply, “How soon can we have them?”

THE TANK IN ACTION

Not soon enough for the first day of the Somme (1 July), unfortunately. The tank would not go into action until the middle of September and then only 30 of them, most of which broke down. However, Haig recognised their worth and ordered several hundred more. He certainly had high hopes of them at Third Ypres in July the following year, just as for his cavalry. But the mud of “Passchendaele” would prove even worse than that of the Somme; the tanks stuck fast and once again the cavalry stood waiting in vain for the breakthrough.

Morale in the new Tank Corps fell, as did the confidence of the rest of the Army in the tank. The corps needed to be given a fighting chance, on ground specially chosen – better drained and not pock-marked with shell craters. HQ Tank Corps therefore proposed an offensive towards Cambrai, the name now almost synonymous with the tank. Originally conceived as a raid – a limited action to show what the tank could do in the right conditions – planning for Cambrai soon became a casualty of the continuing ambition for breakthrough and restoration of the war of movement. Not the least in ambition was the cavalryman commanding Third Army, whose battle it would be – General Sir Julian Byng. In 1757, one of his ancestors, Admiral John Byng, had faced a firing squad pour encourager les autres – for failing to press his attack on a French fleet off Minorca. General Byng was not going to make the same mistake.

He decided to throw all his divisions into the attack and all his allotted fighting tanks – 380 of them (the Tank Corps had 476 machines in all, including spares and various specialist tanks) – leaving himself without reserves. Haig placed virtually the entire Cavalry Corps, some 27,500 cavalrymen and their support troops, under Byng’s command to “pass through and operate in open country”.

The preparations were prodigious. Some of the regiments had to march long distances to the assembly areas – the Queen’s Bays, for example, 106 miles in five night marches; 270 tons of oats and hay had to be pre-positioned. “Cavalry track battalions” were formed, largely of Indian NCOs and sowars (troopers) recently arrived in France as reinforcements, to help get the cavalry forward in the wake of the advancing tanks and infantry, their job to make gaps in the wire and fill-in or bridge the trenches and shell holes. With pick and shovel, assisted by tanks fitted with grapnels to tear up the barbed wire, they were expected to clear paths 60yd wide to a depth of five miles, bridging 26 successive lines of trenches.

DRIVER ADVANCE

The battle began well. On 20 November, in an obliging morning mist and before a single round of artillery had been fired, the 380 tanks answered to the command “Driver, advance!” The absence of the usual artillery notification coupled with the tanks’ quite remarkable success in concealment during the build-up, aided by the Royal Flying Corps’ local air superiority, took the Germans wholly by surprise. When troops reached the forward trenches they found flasks of hot coffee at the firing step – breakfast hastily abandoned. On a six-mile front, checked only at Flesquières, Byng’s divisions were able to penetrate five miles into the defences of the Hindenburg Line that morning, further to date than anywhere on the Somme or in Flanders. By early afternoon, only a half-finished fourth line stood between Third Army and open country and here there was a wide-open gap for several hours.

British cavalry awaiting orders earlier in the year.

An advance of five miles, even a relatively easy one, was tiring, however. By now the tanks were crewed by exhausted men (the noise, the fumes, the concussive vibrations), or were out of action and the infantry could make no further progress without them, for the Germans were still firing back. And if the infantry could make no progress, the cavalry certainly couldn’t. In any case, for whatever reason – poor communications, lack of “dash” in regiments that had been inactive for three years (recriminations would follow) – the cavalry was slow getting forward.

The Germans were certainly expecting them. Leutnant Miles Reinke of 2 Garde-Dragoner Regiment wrote home: “We waited for several regiments of cavalry to sweep up and drive us towards Berlin. But this didn’t happen, much to our surprise.” Indeed, expecting to be overrun at any minute, they had even abandoned Cambrai itself.

DIGGING IN

With no reserve of tanks and infantry to renew the attacks, Byng told his spent troops to dig in and the cavalry, when it did come up in the afternoon, to hold along the St Quentin Canal. German reserves began pouring into the breaches and the following morning, after a night of icy rain, the British faced the predictable counter-attacks. The Second Cavalry Brigade found itself in a sharp dismounted action at Noyelles just after first light. Lieutenant Edward Horner of the 18th Hussars, whose brother-in-law, Raymond Asquith, the eldest son of the former prime minister, had been killed on the Somme the previous year, was fatally wounded that morning. His mother, Lady (Frances) Horner, would commission a memorial bronze by the equestrian artist Alfred Munnings set on a plinth by Sir Edwin Lutyens, which stands today in Mells church in Somerset with Raymond Asquith’s original grave marker.

THE COUNTER-OFFENSIVE

Haig sent more divisions to Cambrai but it was too late. Byng’s renewed attacks on the 22nd and 23rd quickly petered out, while with impressive speed the Germans massed 20 divisions for a counter-offensive. These came out of the morning mist on 30 November after a short, intense bombardment consisting of high explosive, gas and smoke – but with almost no tanks, for the Germans did not rate them. Using new infiltration techniques they thrust at both flanks of the salient created by the Third Army’s advance, breaking through in the south. Byng’s infantry put up a resolute defence and disaster was averted but only with considerable loss, including Brigadier-General Roland Boys Bradford VC, MC – at 25 the youngest brigade commander of modern times, who had been in command for just three weeks.

Dawn, The Sunken Road near La Vacquerie (20th November 1917) by William Lionel Wyllie.

Byng was now forced to abandon the greater part of his original gains. German casualties at Cambrai were around 50,000; the BEF’s were 45,000 (of which 10,000 were dead) yet with nothing to show for it, just the sense of a “near miss”, a demonstration of what the tank could do in the attack if well handled. The church bells, which had rung in England on the first day to announce a resounding victory, had rung prematurely.

Although British and Imperial cavalry were achieving great things in Palestine and Mesopotamia, the conditions on the Western Front were just not right yet for breakthrough. They would have to wait until the late summer of 1918, when the Germans overreached themselves in a last-ditch offensive, to get their promised gallop.

Allan Mallinson’s Too Important for the Generals: How Britain Nearly Lost the First World War is published by Penguin Random House, RRP: £10.