the retreating Army of the Rhine. Despite his misjudgment, Alvensleben held off four French corps for seven hours. The French could have swept away the key Prussian defense and escaped, however, Bazaine had no confidence in his generals or his troops, and contented himself with inflicting severe losses on the most aggressive portions of the German army. Ultimately the aggression and skill of the Prussians prevailed over Bazaine's gross indecision. Citing the need to acquire more ammunition and the distance from the supply trains, Bazaine issued an order on the night of 16–17 August for his army to fall back closer to Metz. The strong defensive positions of the fortress would, he thought, enable him to inflict massive losses on the Germans and crush their armies. After resupplying, Bazaine would begin anew the march to the Meuse on 19 and 20 August. Despite some skirmishing on 17 August, the Prussians did not pursue the French in force, as attacking that day was not their intention. The French withdrew to the Plappeville plateau east of Gravelotte over the course of the day. There the Battle of Gravelotte would be fought on 18 August. Gravelotte and Sedan Two days later, while the French actually retreated on Metz (taking seven hours to cover 5 to 6 miles) the masses of the Germans gathered in front of Bazaine's Army at Gravelotte, intercepting his communication with the interior of France. This Bazaine expected, and feeling certain that the Germans would sooner or later attack him in his chosen position, he made no attempt to interfere with their concentration. The great battle was fought, and having inflicted severe punishment on his assailants, Bazaine fell back within the entrenched camp of Metz. But although he made no appeals for help, the only remaining army of France, Marshal Mac-Mahon's Army of Châlons, moved to rescue Bazaine. Napoleon III followed close behind MacMahon's army in a carriage. When on 2 September 1870, MacMahon blundered into a German trap at Sedan, the Emperor mounted a horse despite his pain, rode along the firing line for hours seeking death. It never found him. Napoleon III surrendered with 80,000 men. With Sedan the Second Empire collapsed, Napoleon III being taken as a prisoner of war. Siege of Metz The Prussian army of 200,000 men now besieged the city of Metz, where 3 French marshals, 50 generals, 135,000 men, and 600 guns were