Battle of Sedan (1870)

Background

In July 1870 France declared war on Prussia after Bismarck's publication of the edited Ems telegram, and the states of the North German Confederation, Bavaria, Baden and Württemberg mobilised alongside her. Moltke's General Staff and railways put the German armies into the field faster, and after the August defeats Marshal Bazaine's Army of the Rhine was shut up in Metz, besieged from 19 August.

A second French army was assembled at Châlons from I, V, VII and XII Corps and placed under Marshal MacMahon, with Napoleon III travelling with it. MacMahon first meant to fall back on Paris and fight under its fortifications. Under pressure from the Empress and the ministry in Paris, and misled by ambiguous messages from Bazaine, he instead set out on 23 August to relieve Metz by a long detour to the north-east, close to the Belgian frontier. The march began in pouring rain, short of food, and soon drifted north to the magazines at Rethel.

Moltke at first expected the French to cover Paris, but once their direction was clear he swung the Third Army and the new Army of the Meuse northwards against MacMahon's exposed flank. On 30 August they caught de Failly's V Corps at Beaumont, and the French lost about 7,500 men and 40 guns. MacMahon fell back across the Meuse to the small fortress of Sedan to rest, feed and re-equip his men before retreating west to Mézières. On 31 August the exhausted army could not march; orders to blow the Meuse bridges at Bazeilles and Donchery were not carried out, and by nightfall the Germans held every crossing and were closing from east and west.

The armies

The Army of Châlons had been formed with 166 battalions, 100 squadrons and 380 guns. At Sedan it counted some 120,000–130,000 men in 202 battalions, 80 squadrons and 564 guns, organised as Ducrot's I Corps, V Corps (de Failly, replaced by Wimpffen), Félix Douay's VII Corps and Lebrun's XII Corps, with Margueritte's reserve cavalry division. It was badly shaken: worn out by marching to and fro in the rain, hungry, and demoralised by Beaumont. Its best troops were XII Corps' four regiments of marine infantry, the 'Blue Division'. French infantry carried the Chassepot, with an effective range of about 1,500 metres against about 600 for the Prussian Dreyse needle gun, and the army had mitrailleuse batteries. Its artillery was rifled bronze muzzle-loaders using time fuses.

Moltke directed two armies, with King Wilhelm I and Bismarck present: the Crown Prince of Prussia's Third Army (V and XI Prussian Corps, I and II Bavarian Corps and the Württemberg division) and the Crown Prince of Saxony's Army of the Meuse (Guard, IV and XII Saxon Corps). Together they had some 200,000–224,000 men, 222 battalions, 186 squadrons and 774 guns. Their decisive advantage was artillery: Krupp steel breech-loaders firing percussion-fused shell, with longer range and a higher rate of fire than the French guns.

The battle

CDB90 records the battle as a single engagement, number 225 (SEDAN), from 04:00 to 17:00 on 1 September. The French held a triangle north and east of the fortress: the Givonne valley on the east, the Floing brook on the west and the Calvary of Illy, backed by the Bois de la Garenne, at the apex. Times below follow Moltke's account; other sources differ by up to an hour.

Bazeilles and the Givonne (04:00–10:00). At about 04:00, in thick mist, von der Tann sent his 1st Bavarian Brigade across the pontoon bridges into Bazeilles. They found the streets barricaded and were fired on from every house. XII Corps' marines, reinforced by brigades of I and V Corps, fought them house by house; the struggle for the Villa Beurmann, which commanded the main street, lasted an hour. Inhabitants joined the fighting, and both sides later traded accusations over it. North of the village the Saxon advance guard took La Moncelle from about 05:00 and held the houses beyond the Givonne.

The French command crisis (06:00–09:00). MacMahon was hit by a shell splinter near La Moncelle at about 06:00 and named Ducrot to succeed him. Ducrot, told at about 07:00, ordered the army to assemble at Illy for a retreat on Mézières. Wimpffen, newly arrived from Algeria to take over V Corps, held a commission from the War Minister to command the army if MacMahon fell. Judging Mézières hopeless, he produced it, cancelled Ducrot's orders and tried instead to break out east towards Carignan and Bazaine. The divisions already marching north were recalled. Bazeilles fell to the Bavarians, reinforced by the Prussian 8th Division, through the morning, and the Saxons and Bavarians took Daigny.

The northern jaw (06:00–12:00). The Crown Prince's V and XI Corps had crossed the Meuse at Donchery by 06:00. Hearing the guns at Bazeilles, they swung right through the unguarded defile of St Albert towards St Menges and Fleigneux. At about 09:00 General Galliffet led Chasseurs d'Afrique and lancers against the first Prussian batteries and infantry; they were driven off by rifle fire at sixty yards and shell fire. By 10:00 fourteen batteries of XI Corps were in action near St Menges, and around midday the Guard hussars coming from the east met the Third Army: the ring was closed.

The cauldron (12:00–15:00). Some 26 German batteries now crossed their fire with the Guard artillery east of the Givonne, wrecking the French gun line. Douay retook the Calvary of Illy but lost it by 14:00. To relieve Liebert's division on the heights above Floing, Margueritte led his light cavalry out of the Bois de la Garenne. He fell mortally wounded almost at once, and Galliffet led the charges that followed, repeated for about half an hour against the 43rd Brigade and the troops around Floing. Some troopers rode through gun intervals and reached the St Albert defile, but volleys at short range broke them, at a cost of 791 killed and wounded. Liebert's men fell back to the Garenne wood at about 15:00. At about the same time Wimpffen's eastward attack from Fond de Givonne, and a briefly successful thrust into Balan, were thrown back.

Surrender (15:00–17:00 and 2 September). The Prussian Guard and Saxons cleared the Bois de la Garenne by 17:00, taking prisoners by the thousand, while broken columns poured into Sedan under shell fire. At about 16:30 white flags appeared. Napoleon sent General Reille to King Wilhelm on the heights at Frénois offering his sword. Overnight at Donchery, Moltke insisted on the surrender of the whole army, and Wimpffen signed the capitulation on the morning of 2 September.

Aftermath

The Germans lost about 9,000–9,900 men. French killed and wounded were about 17,000–18,000, and 21,000 more were taken during the fighting. The capitulation added 83,000, making some 104,000 prisoners, besides about 3,000 disarmed in Belgium. The spoils included 419 field guns, 139 fortress guns, 66,000 rifles, over 1,000 wagons and 6,000 horses. The prisoners were held on the Iges peninsula, in a bend of the Meuse, short of food, before being marched off to Germany. Napoleon went into comfortable captivity at Wilhelmshöhe near Kassel.

With one army destroyed and the other locked in Metz, France had lost the regular war. When the news reached Paris, the Empire fell: a republic and a Government of National Defence were proclaimed on 4 September and fought on for five more months. The siege of Paris began on 19 September. Having captured the Emperor, Prussia now had no government to make a quick peace with.

Germans kept 2 September as Sedantag until 1919. Moltke himself thought the 1st, not the day of the surrender, deserved remembering. Moltke judged MacMahon lucky to have been wounded before he had to sign, since he later sat in judgment on Bazaine, the comrade he had failed to relieve. Wimpffen, who had arrived only days before, bore the capitulation, and his cancelling of Ducrot's retreat left the army with conflicting orders at the crisis of the day. What happened at Bazeilles remains disputed: German accounts stress armed civilians, French ones the killing of inhabitants.

Wargaming it

Sedan is a set-piece encirclement, which makes it tricky to balance and fascinating to study. The whole battle fits a corps or division-level game with brigades as units and hour-long turns, on a table that runs from the Donchery crossings in the west to the Givonne valley in the east. Bazeilles makes a superb street-fighting scenario at battalion or company level, and the Floing charges a short, brutal cavalry-against-rifles game.

The key terrain is the river line and the valleys: the Meuse bridges, the Givonne valley, the Floing brook, the Calvary of Illy, the Bois de la Garenne and the defile of St Albert, which the French left unguarded. German artillery must dominate: rules need long-range breech-loading guns that can silence French batteries and wreck formed troops in the open, while Chassepot fire punishes careless infantry assaults.

The decisions are French ones. Should MacMahon march for Mézières on 31 August instead of resting? Should the bridges at Bazeilles and Donchery be blown, or Douay be allowed to dig in? The richest what-if is the command crisis. A random-event or hidden-orders system can test what happens if Ducrot's retreat on Illy and Mézières goes ahead at 07:00, or if Wimpffen's eastern breakout gets an hour's start. Victory conditions should measure how much of the French army gets out, or how long Illy holds, not whether the French win. The German player faces a race against the clock to close the ring before 12:00.

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