The siege of Soissons which took place from September 11 to October 16, 1870, was an episode of the Franco-Prussian War of which ended with the surrender of the city.
Background
Soissons had already fallen to the Prussians in 1814 during the Napoleonic Wars. After the Battle of Sedan , the Maas Group of Germany has continued on in its way to Paris , and the money infantry of Corps No. IV of Prussia, a portion of the general Army Group, this came before the siege of the fortress Soissons on September 11, 1870. The Soissons defended the city and rejected Major von Wittich's offer to withdraw from the German General Staff. The topography of the area suggested that to lay siege to the fortress, the Germans needed to be well prepared. As the advance to Paris needed to be expedited, the formations of the Prussian IV Corps were ordered out of the area for the time being, and Soissons was placed under German supervision until the General. On September 6, the bridges that connected to Villeneuve-Saint-Germain , Saint-Mard , Missy-sur-Aisne and Condéare were destroyed and the Vauxaillon and Vierzy tunnels are blocked. On September 9, the presence of white cuirassiers 4th corps commanded by General Alvensleben is reported in the district of Soissons. The Germans sent their troops to the Wailly bridge was it was not yet destroyed.
The Fortifications
Located at the junction of major roads and railways from Paris to Reims, as well as that of Paris to Laon by Villers-Cotterets, its location was considered important. However, the mountains which dominated the city being devoid of fortified works, make it a real bottom of a basin, a real shell nest.
The fortifications of Soissons consisted of a continuous wall covered with 11 bastions. This enclosure was casemated in various places, but not enough to shelter the garrison. It was based on the Aisne to the North and to the South and it formed a quadrilateral of approximately 1,200 meters by 800 meters. The Saint-Vaast suburb was not included in this quadrilateral, but also formed an enclosure also leaning on the Aisne, to the east, and was covered with 3 bastions . A military dam, built on the river, near and upstream of the stone bridge, and a diversion from the Depression, allowed most of the ditches to be submerged and the bottom of the two valleys to be flooded. Only a portion of the ditches, that of the southwest, because of its higher position, couldn't be flooded. With the exception of this point, the place of Soissons could not be taken by force, but it was unable to withstand a siege in a good condition for long.
On the eve of the war, Soissons was considered the key to Paris, but nothing had been done to put this stronghold in the state of the strategic importance attributed to it.
The Garrison
At the time of the declaration of war , the garrison of Soissons consisted of 3 battalions of the 15th line infantry regiment, under the orders of Colonel Théodore Eugène Fraboulet de Kerléadec. There were, however, no artillerymen or artillery teams. On July 20, the 15th RIL left Soissons to join the Army of the Rhine. The July 22 arrival of brigades spoiler Sonnay and Colin of 3 E Division 6 th Army Corps of the Army of the Rhineunder the orders of General Lafond de Villiers who joined theAugust 2ndthe Châlons camp. From August 2 to 10 the place is absolutely without garrison. On August 11, under the Decree of July 17, 1870 which called the mobile guards under the flags, the 2nd mobile battalion of the Aisne ( district of Soissons ) garrisoned there. On August 12, arrival of 1st Battalion of mobile Aisne (district of Château-Thierry) On August 17, arrives 6 th battalion of mobile Aisne (district of Vervins) At about the same date, the depot battalion of the 15th line infantry regimentarrived from Laon. This was made up of 2 companies of 800 men each with barely 10 officers to command them. They were reinforced by elements escaped from Sedan which formed 2 additional companies. The August 20 arriving from the 1st battery of the 8th artillery regiment . On August 27, starting from 1st battalion of mobile Aisne for Villers-Cotterets and Paris That same day, the government recalled former soldiers aged 25 to 35, who were armed with old piston rifles, and created the rural national guards. These were transformed into marching regiments. Thus the 2 battalions of Soissons formed the 17th marching regiment .
At the start of the siege the city was defended by 4,425 men: