General von Werder meanwhile had occupied Vesoul, and had the south face of the city put in a state of defence.
The only event of importance during the course of October which remains to be mentioned was the action taken against the French forts lying rearward of the German armies.
At the beginning of the month the newly constituted 4th Reserve Division, of fifteen battalions, eight squadrons, thirty-six guns, and a company of fortress-pioneers, had assembled in Baden, and crossed the Rhine at Neuenburg. The vicinity was first cleared of franctireurs, Mülhausen was occupied, and, by the express desire of its municipal authorities, the excited artisan inhabitants were disarmed. General von Schmeling (commanding the Division) was instructed to besiege Neu-Breisach and Schlettstadt, and at once set about the investment of each of these places with a brigade. On October 7th the East Prussian Landwehr invested Breisach, and the field-batteries shelled the place, but without effect. The other brigade, having been forced to detach considerably, reached Schlettstadt very weak, but was reinforced by Etappen troops to such extent that the place was invested with 8 battalions, 2 squadrons, and 2 batteries. At the same time 12 companies of fortress-artillery and 4 companies of pioneers arrived from Strasburg with the necessary siege material, and an artillery park of fifty-six heavy guns was established at St. Pilt; the engineer park was located at Kinzheim.
At the beginning of the blockade, inundations and marsh-land rendered Schlettstadt, a fortified town of 10,000 inhabitants, unapproachable on the east and south, and partly on the north. The place itself, perfectly safe from storm, with high walls and a wet ditch, was armed with 120 guns, but garrisoned with only 2000 men, for the most part Gardes-Mobiles. There was a deficiency of safe casemates, and on the west front vineyards and hedgerows favoured the near approach of assaults, while the railway embankment was a ready-made protecting wall for the construction of the first parallel. To divert the attention of the besieged from this front of attack, a battery was constructed on the 20th at the Kappel Mill on the south-east, from which fire was opened on the barracks and magazine in the town, and on the sluice which maintained the inundation. By the evening of the 21st, the infantry posts had advanced to within 400 paces of the glacis, and the construction of the first parallel was proceeded with that night, immediately behind the railway, as well as of emplacements for six batteries within 1230 feet from the ramparts. The garrison fired in the dark on the entire field of attack, but almost without effect. By the morning the trenches were two feet wide and three and a half feet deep, and 20 heavy guns and 8 mortars were ready to open fire. A hot artillery duel now began with the fortress, which replied very steadily. The battery at the mill subjected the west front to a telling reverse fire, and several guns and embrasures were severely damaged. The town was fired at several points, and the defenders' fire gradually ceased. During the night, which was very stormy, the batteries of the attack kept up their fire, the parallel was widened and two new batteries were begun.