The astute tactician at once determined to make every effort to prevent this concentration of his opponents, and by the evening of the 15th a cavalry division had crossed the Moselle and reached the village of Mars-la-Tour, where it bivouacked for the night. It had seen troops in motion towards Metz, but did not know whether these formed the rear-guard or the vanguard of the French army in its march towards Verdun. In fact, Bazaine had not yet got away with his army. All the roads from Metz were blocked with heavy baggage, and it was impossible to move so large an army with expedition. The time thus lost by Bazaine was diligently improved by Frederick Charles, and on the morning of the 16th the Brandenburg army corps, one of the best and bravest in the German army, had followed the cavalry and come within sight of the Verdun road. It was quickly perceived that a French force was before them, and some preliminary skirmishing developed the enemy in such strength as to convince the leader of the corps that he had in his front the whole or the greater part of Bazaine's army, and that its escape from Metz had not been achieved. [=The Battle of Mars-la-Tour=] They were desperate odds with which the brave Brandenburgers had to contend, but they had been sent to hold the French until reinforcements could arrive, and they were determined to resist to the death. For nearly six hours they resisted, with unsurpassed courage, the fierce onslaughts of the French, though at a cost in life that perilously depleted the gallant corps. Then, about four o'clock in the afternoon, Prince Frederick Charles came up with reinforcements to their support and the desperate contest became more even. [=Defeat of the French=] Gradually fortune decided in favor of the Germans, and by the time night had come they were practically victorious, the field of Mars-la-Tour, after the day's struggle, remaining in their hands. But they were utterly exhausted, their horses were worn out, and most of their ammunition was spent, and though their impetuous commander forced them to a new attack, it led to a useless loss of life, for their powers of fighting were gone. They had achieved their purpose, that of preventing the escape of Bazaine, though at a fearful loss, amounting to about 16,000 men on each side. "The battle of Vionville [Mars-la-Tour] is without a parallel in military history," said Emperor William, "seeing that a single army corps, about 20,000 men strong, hung on to and repulsed an enemy more than five times as numerous and well equipped. Such was the glorious deed done by the Brandenburgers, and the Hohenzollerns will never forget the debt they owe to their devotion." [=Great Victory of the Germans at Gravelotte=]