By it nearly one half of all the French troops in the field were effectually shut up within a surrounded fortress; while the Germans, leaving the greater part of the first and second armies as a besieging force before the city, were free to execute the movement which was now at once begun-the advance against the army of MacMahon, which was reorganizing at Chalons, reenforced by Failly's corps, a part of Felix Douay's, and numerous reserves. For the purpose of this and of further movements, the organization of the German forces was now somewhat changed. A fourth army was formed, under command of the crown prince of Saxony, from portions of the other armies, and from the troops who had up to this time been engaged in guarding the German coasts against a naval attack, which was hardly to be any longer feared. Less important changes were also made in the organization of the first and second armies, and the forces of the third were considerably increased. The advance of the last named body and of the army of the crown prince of Saxony was begun on the 19th, the very day after the battle of Gravelotte; the king of Prussia assuming the command of the united force, which was now to enter upon operations which continued to the gates of Paris. The army under the crown prince of Saxony (army of the Meuse, as it came to be called) advanced along the highway toward Chalons. The third army at the same time crossed the Meuse and advanced toward Bar-le-Duc. Toul had been previously attacked, and a besieging force was now left to invest it, while the remainder of the army continued its progress.

In its gradual advance it was met by the news that MacMahon had withdrawn from Chalons, and had taken up his march to Rheims, and beyond it in the direction of Bethel, evidently with the intention of relieving Bazaine's army. In consequence of this intelligence the German march was immediately turned northward, in order to intercept the French army and occupy a position between it and Bazaine. The opposing armies rapidly approached each other, as the French pressed forward from the neighborhood of Vouziers along the Meuse; and after several minor engagements between detached parties, on Aug. 30 a large body of the Germans surprised the corps of Gen. Failly in their camp near Beaumont, drove them from it, and after both sides had been reenforced began a battle which resulted in the retreat of the French beyond the Meuse and their further withdrawal toward Sedan. Here MacMahon massed his army and prepared fur a more important conflict. The emperor Napoleon was now with this portion of his forces.

After the first defeats he had relinquished the command of the armies to his marshals (Aug. 8), and the management of affairs in the capital to a new ministry (Pali-kao's) under the empress regent; and leaving Metz immediately after the battle of Courcelles, he had gone to MacMahon at Chalons. The prince imperial had been sent to Belgium when the situation had first become critical. The opposing forces were now prepared for an inevitable and decisive engagement. The battle of Sedan was begun by the Germans Sept. 1. The troops of the army of the Meuse and the third army, by a series of manoeuvres and after severe fighting, drove the French from all sides to that fortress, where, almost surrounded, entirely defeated, and without provisions or defences sufficient to endure a siege even of a day, they were compelled to capitulate. The emperor surrendered himself to King William in person, Sept. 2, and was carried a prisoner to Wilhelmshohe. In dead, wounded, and the vast number of prisoners of war, the French had thus lost in a few days an army of nearly 150,000 men.

The news of Sedan created intense excitement at Paris. In the night of Sept. 3-4 Jules Favre demanded in the corps legislatif the deposition of the emperor and his dynasty; the popular indignation against Napoleon and his party was without bounds. On the 4th the people filled the streets and thronged to the hall of the corps legislatif and thence to the hotel de ville. Here Gambetta, in the midst of the most tumultuous applause, proclaimed the republic; and a provisional government of national defence was at once formed. This was under the presidency of Gen. Trochu and the vice-presidency of Favre, and included Emmanuel Arago, Cre'mieux, Ferry, Gambetta, Garnier-Pages, Glais-Bizoin, Pelletan, Picard, Rochefort, and Simon. In the evening a decree of the new government declared the corps legislatif dissolved and the senate abolished. Jules Favre was placed in charge of foreign affairs. The empress fled from Paris and took refuge in England. The government of national defence issued an address to the arm?; and a circular was sent to the European powers explaining the attitude of France. The most energetic measures were begun for putting Paris in a position for defence.

Later in the month Favre had an interview with Bismarck at Ferrieres, in which he unsuccessfully sought to negotiate terms of peace. A similar purpose was the cause of a visit of Thiers to the principal European courts. The elections for a national assembly, to immediately regulate affairs, which were decreed during the month by the government of national defence, were postponed from time to time on account of the difficulty of communicating with the country at large. After the battle of Sedan there was but little to impede the advance of the German army to the capital. On the 5th they entered Rheims, and only minor skirmishes and trifling engagements attended their further march, until on the 15th they had closely approached Paris, advancing in the general form of a half circle. A sortie by Gen. Ducrot on the 19th was repulsed, and a few days later the actual investment of the city was begun, with the army of the Meuse on the northern and northeastern sides, the third army on the southern and southeastern, and bodies of cavalry guarding the approaches to the western front.