Battle of Sedan ( 1870 ) The Battle of Sedan was fought during the Franco – Prussian War on 1 September 1870 . It resulted in the capture of Emperor Napoleon III and large numbers of his troops and for all intents and purposes decided the war in favour of Prussia and its allies , though fighting continued under a new French government . The 120 , 000 strong French " Army of Châlons " , commanded by Marshal Patrice de Mac - Mahon and accompanied by Napoleon III , was attempting to lift the Siege of Metz , only to be caught by the Prussia n Meuse Army and defeated at the Battle of Beaumont . The Meuse Army and the Prussian Third Army , commanded by Field - Marshal Helmuth von Moltke and accompanied by Prussian King Wilhelm I and Prussian Chancellor Otto von Bismarck , cornered MacMahon ' s army at Sedan in a massive encirclement battle . Marshal MacMahon was wounded during the attacks and command passed to General Auguste - Alexandre Ducrot . Background . After its defeat at Gravelotte , Marshal Bazaine ' s " Army of the Rhine " retreated to Metz where it was besieged by over 150 , 000 Prussian troops of the First and Second Armies ( Siege of Metz ) . Emperor Napoleon III , along with Marshal MacMahon , formed the new French " Army of Châlons " to march on to Metz to rescue Bazaine . With Napoleon III personally leading the army , with Marshal MacMahon in attendance , they led the " Army of Châlons " in a left - flanking march northeast towards the Belgian border in an attempt to avoid the Prussians before striking south to link up with Bazaine . The Prussians had repeatedly outmaneuvered the French in the string of victories through August 1870 , and the march both depleted the French forces and left both flanks exposed . The Prussians , under the command of von Moltke , took advantage of this maneuver to catch the French in a pincer grip . Leaving the Prussian First and Second Armies besieging Metz , Moltke took the Prussian Third Army and the Army of the Meuse northward where they caught up with the French at Beaumont - en - Argonne on 30 August . After a hard - fought battle with the French losing 5 , 000 men and 40 cannons in a sharp fight , the French withdrew towards Sedan . Their intention was to rest the army , which had been involved in a long series of marches , resupply them with ammunition and then retreat , rather than giving battle in the town . Having reformed in Sedan , the " Army of Châlons " deployed the First Corps to check the Prussian advance , but was immediately isolated by the converging Prussian armies . They could not retreat owing to the exhaustion of their troops , and they were short on ammunition . The French rear was protected by the Fortress of Sedan , and offered a defensive position at Calvaire d ' Illy , which had both hills and woods to provide cover for any defense . Moltke divided his forces into three groups : one to detain the French where they were , another to race forward and catch them if they retreated , and a third ( the smallest force ) to hold the river bank . The French were unable to move and had to fight " where they stood " . The Prussians thus encircled the French . Battle . The battle opened with the " Army of Châlons " , with 202 infantry battalions , 80 cavalry squadrons and 564 guns , attacking the surrounding Prussian Third and Meuse Armies , which totaled 222 infantry battalions , 186 cavalry squadrons and 774 guns . Napoleon had ordered MacMahon to break out of the encirclement , and the only point where that seemed possible was at La Moncelle , whose flank was protected by a fortified town . The Prussians also picked La Moncelle as one point where they would mount a breakthrough . Prince George of Saxony and the Prussian XI Corps was assigned to the task , and General Baron von der Tann were ordered to attack Bazeilles on the right flank . This was the opening engagement , as the French First Corps had barricaded the streets , and enlisted the aid of the population . Von der Tann sent a brigade across pontoon bridges at 0400 hours , but encountered stiff resistance , holding only the southern end of the town . The combat drew new forces , as French brigades from the First , Fifth and Twelfth Corps arrived . At 0800 the Prussian 8th Infantry Division arrived , and von der Tann decided it was time for a decisive attack . He had not been able to bring artillery to bear from long range , so he committed his last brigade to storm the town , supported by artillery from the other side of the Meuse . His artillery reached the Bazeilles at 0900 hours . The fighting continued to spread to the south of the town , and the 8th Infantry Division was sent to reinforce the Bavarians fighting at La Moncelle , where they had attempted to mount a breakthrough of the French defense . Fighting began in earnest at 0600 , and the wounded MacMahon had appointed General Auguste Ducrot to command , who received the news at 0700 . Ducrot ordered the retreat that Moltke had expected , but was overruled almost immediately by General de Wimpffen , who threw his forces against the Saxon s at La Moncelle . This led to a brief rally for the French , who drove back the artillery around La Moncelle and pressed the Bavarians and the Saxons . However , with the taking of Bazeilles , and the arrival of fresh waves of Prussian troops , the counter - attack began to collapse . But by 1100 hours , Prussian artillery took a toll on the French , while more Prussian troops arrived on the battlefield . After an intense bombardment and Prussian attacks from the northwest and east , and Bavarian attacks from the southwest , the " Army of Châlons " was driven into the Bois de la Garenne and surrounded . The French cavalry , commanded by General Jean Auguste Margueritte , launched three desperate attacks on the nearby village of Floing where the Prussian XI Corps was concentrated . Margueritte was mortally wounded leading the very first charge and the two additional charges led to nothing but heavy losses . Conclusion and aftermath . By the end of the day , with no hope of breaking out , Napoleon III called off the attacks . The French lost over 17 , 000 men killed and wounded with 21 , 000 captured . The Prussians reported their losses at 2 , 320 killed , 5 , 980 wounded and 700 captured or missing . By the next day , on 2 September , Napoleon III ordered the white flag to be run up and surrendered himself and the entire " Army of Châlons " to Moltke and the Prussian King . The capture of the French emperor left the Prussians without an opposing government willing to make a quick peace . Indeed , two days after news hit Paris of Emperor Napoleon ' s III capture , the French Second Empire collapsed in a bloodless revolution , leading to the creation of a new provisional government which would carry on the war for five more months , sparing no effort to try to change France ' s fortunes . However , the defeat at Sedan and the capture of Napoleon III sealed the doom of France and thus decided the outcome of the war in Prussia ' s favor . With the Second Empire overthrown , Napoleon III was permitted to leave Prussian custody for exile in England , while , within a fortnight , the Prussian Meuse Army and the Third Army went on to besiege Paris . The debacle at Sedan was to haunt Napoleon III for the rest of his life . In 1873 , Napoleon III ' s last words were addressed to his friend , doctor Henri Conneau : And he died shortly after . In recognition of the role this battle played in German Unification , many Germans celebrated Sedantag ( Day of Sedan ) on each 2 September until 1919 . The Kaiser himself refused to declare 2 September as an official holiday ; instead , it became an unofficial day of celebration .