The final phase of the battle of the Somme saw the first use of the tank on the battlefield. The Allies prepared an attack that would involve 13 British and Imperial divisions and four French corps. The attack made early progress, advancing in places but the tanks had little effect due to their lack of numbers and mechanical unreliability. The final phase of the battle took place in October and early November, again producing limited gains with heavy loss of life. All told, the Somme battle had made penetrations of only and failed to reach the original objectives. The British had suffered about 420,000 casualties and the French around 200,000. It is estimated that the Germans lost 465,000, although this figure is controversial.