On 20 November the British launched the first massed tank attack and the first attack using predicted artillery-fire (aiming artillery without firing the guns to obtain target data) at the Battle of Cambrai. The Allies attacked with 324 tanks (with one-third held in reserve) and twelve divisions, advancing behind a hurricane bombardment, against two German divisions. The machines carried fascines on their fronts to bridge trenches and the German tank traps. Special "grapnel tanks" towed hooks to pull away the German barbed wire. The attack was a great success for the British, who penetrated further in six hours than at the Third Ypres in four months, at a cost of only 4,000 British casualties. The advance produced an awkward salient and a surprise German counter-offensive began on 30 November, which drove back the British in the south and failed in the north. Despite the reversal, the attack was seen as a success by the Allies, proving that tanks could overcome trench defences. The Germans realised that the use of tanks by the Allies posed a new threat to any defensive strategy they might mount. The battle had also seen the first mass use of German Stosstruppen on the Western front in the attack, who used infantry infiltration tactics to penetrate British defences, bypassing resistance and quickly advancing into the British rear.
