Napoleon's object being surprise, all the cavalry except a few vedettes were kept back behind the leading infantry columns and these latter were ordered to advance, on the signal being given, in "masses of manoeuvre," so as to crush at once any out post resistance which was calculated upon the time required for the deployment of ordinary marching columns. This order has never since found an imitator, but deserves attentive study as a masterpiece (see H. Bonnal, Manoeuvre dIena).
To meet the impending blow the Prussians had been extended in a cordon along the great road leading from Mainz to Dresden, Blucher was at Erfurt, Rtichel at Gotha, Hohenlohe at Weimar, Saxons in Dresden, with outposts along the frontier. An offensive move into Franconia was under discussion, and for this purpose the Prussian staff had commenced a lateral concentration about Weimar, Jena and Naumburg when the storm burst upon them. The emperor gathered little from the confused reports of their purposeless manoeuvres, but, secure in the midst of his "battalion square" of 200,000 men, he remained quite indifferent, well know ing that an advance straight on Berlin must force his enemy to concentrate and fight, and as they would bring at most 127,000 men on to the battlefield the result could hardly be doubtful. On Oct. 9 the cloud burst. Out of the forests which clothe the northern slopes of the Thuringer Wald the French streamed forth, easily overpowering the resistance of the Prussian outposts on the upper Saale, and once the open country was reached the cavalry under Murat trotted to the front, closely followed by Bernadotte's corps as "general advance guard." The result of the cavalry scouting was, however, unsatisfactory. On the night of the loth, the emperor was still unaware of the position of his principal foe, and Murat with Bernadotte behind him was directed on Gera for the i 1 th, the remainder of the army continuing along the roads previously assigned to them.
In the meanwhile, however, the Saxons had been moving from Naumburg through Gera on Jena, Hohenlohe was near Weimar, and all the other divisions of the Prussian army had closed in a march eastwards, the idea of an offensive to the southward which Napoleon had himself attributed to them having already dis appeared.
Reaching Gera at 9 A.M. Murat reported the movement of the Saxons on the previous day, but omitted to send a strong detach ment in pursuit. The traces of the Saxons were lost, and Napoleon, little satisfied with his cavalry, authorized Lasalle to offer up to 6,000 frs. reward for information of the Prussian point of con centration. At I A.M. of the 12th Napoleon issued his orders : Murat and Bernadotte via Zeitz to Naumburg; Davout (III. corps and a dragoon division) also to Naumburg; Lannes to Jena, Augereau following; Soult to Gera.
In the meantime the Prussians were effecting their concentra tion. Riichel, who with 15,000 men had been sent into the moun tains as an advance guard for the projected offensive, was recalled to Weimar, which he reached on the i3th. The main body were between Weimar and Apolda during the 12th, and the Saxons duly effected their junction with Hohenlohe in the vicinity of Vierzehnheiligen, whilst the latter had withdrawn his troops, all but some outposts from Jena, to the plateau about Capellen dorf, some 4m. to the N.W. The whole army, of over 120,000 men, could therefore have been concentrated against Lannes and Augereau by the afternoon of the 13th, whilst Soult could only have intervened very late in the day, and Davout and Bernadotte were still too distant to reach the battlefield before the 14th. All the French corps, moreover, were so exhausted by their rapid marches over bad roads that the emperor actually ordered (at 1 A.M. on the 13th) a day of rest for all except Davout, Bernadotte, Lannes and Murat.
The Prussian headquarters, however, spent the 12th and 13th in idle discussion, whilst the troop commanders exerted them selves to obtain some alleviation for the suffering of their starv ing men. The defeats undergone by their outpost detachment had profoundly affected the nerves of the troops, and on the after noon of the i i th, on the false alarm of a French approach, a panic broke out in the streets of Jena, and it took all the energy of Hohenlohe and his staff to restore order. On the morning of the 12th the Saxon commanding officers approached Hohenlohe with a statement of the famishing condition of their men, and threatened to withdraw them again to Saxony. Hohenlohe pointed out that the Prussians were equally badly off, but promised to do his best to help his allies. Urgent messages were sent off to the Commissary von Goethe (the poet), at Weimar for permis sion to requisition food and firewood. These requests, however, remained unanswered, and the Prussians and Saxons spent the night before the battle shivering in their miserable bivouacs.