The Battle of Cambrai began with a secret deployment of British reinforcements for the attack. Instead of a long period of artillery registration (firing ranging shots before the attack) and wire-cutting, which would have warned the German defence that an assault was being prepared, massed artillery-fire did not begin until the infantry–tank advance began on 20 November, using unregistered (predicted) fire. The British sent to roll through the (Hindenburg Line) barbed-wire fields, as a substitute for a long wire-cutting bombardment and the ground assault was accompanied by a large number of ground-attack aircraft. The British attack broke through the but was contained in the rear battlezone () by the , which had been built on the east side of the St Quentin canal on this part of the front. Preparations for a further advance were hampered by the obstacles of the Hindenburg defences, which had been crossed but which limited the routes by which the most advanced British forces could be supplied. The German defence quickly recovered and on 30 November began a counter-offensive, using a similar short bombardment, air attacks and storm troop infantry tactics, which was contained by the British, in some parts of the battlefield using the Hindenburg Line defences captured earlier.