At 6.20am on 20 November 1917 the British Army launched a surprise attack using tanks that created a major break in the German lines.
In the vanguard of the assault, over 400 tanks rolled forward on ideal ground towards the French town of Cambrai. This was the first large tank attack in history and it was devastatingly effective.
The Mark I tank had made its debut on the Somme in September 1916. Success was modest, but British Commander-in-Chief, Sir Douglas Haig, showed his faith in its potential when he ordered 1,000 more for 1917. Tanks were deployed in the early battles of 1917, but in smaller numbers and across boggy Flanders mud.
Tank Corps commanders were frustrated that they had been unable to demonstrate the effectiveness of their machinery – but Cambrai was the moment they had been waiting for.
The new Mark IV tank was almost identical to the Mark I, but it had thicker armour, an improved fuel supply and modified sponsons. The tank pushed contemporary technology to its limit and as a result the vehicles tended to lack the reliability that might be expected from combat vehicles today.
Each tank had a crew of eight men, tightly packed into a metal compartment around an engine that generated unbearable heat and noise. The sound was exacerbated with the thunder of the tracks, weapons and enemy fire striking the armour.
Mark IV tank
At 3mph, it was slow and required half of its crew just to steer it. The atmosphere inside was a choking combination of exhaust fumes, hot oil, petrol, as well as expended cordite from the guns.
Without suspension the crew could be thrown about inside, suffering broken bones and concussion. As the cab filled with carbon monoxide, oxygen starvation caused nausea and headaches. It was difficult, dangerous and uncomfortable work.
But the early tank crews were unflinching pioneers and at Cambrai the tank was finally used for the purpose it was intended; it was a large scale co-ordinated deployment which punched right through the German positions, causing confusion and panic amongst the Germans.
With crews protected from machine gun fire and supported by new artillery techniques, the tanks pushed across no man’s land, through the otherwise impenetrable mass of barbed wire and into the Hindenburg defences, where they proceeded to lay heavy fire down the length of the trenches and roll up the flanks of the penetration.
An artists impression of tanks advancing at Cambrai
By 4pm the tanks had advanced seven miles, affecting the most rapid advance of the war. To put this in perspective, a similarly sized penetration had taken three months and cost 250,000 casualties.
Unfortunately, the Army weren’t able to take advantage of the advances made. Mobile reserves were not available in sufficient numbers or in time to exploit the situation. Likewise, the Cavalry, for whom special routes had been prepared, found it impossible to advance in the face of barbed wire and machine-gun fire so the advance petered out.
When the German Army counter-attacked at the end of the month they recaptured much that had been gained. However, The Tank Corps had sealed their place in history, demonstrating their potential for breaking the deadlock of trench warfare.
Losses for The Tank Corps at Cambrai were not modest; 112 tanks were destroyed and 64 damaged beyond repair. 1,068 officers and men were casualties. But the tank had shown what it could do when appropriately deployed, with Haig writing that the “great value of tanks in the offensive has been conclusively proved.”