Battle of Cambrai — Mass Tank Assault

The British used 476 tanks en masse for the first time at Cambrai, achieving a breakthrough of up to 7 km on the first day—more than had been gained in months at Passchendaele. Church bells rang in London in premature celebration. However, reserves were lacking and a German counterattack on November 30 recovered most of the ground. Though Cambrai showed the tank's potential, it also revealed the inability to exploit a breakthrough without adequate mobile reserves.