Napoleon could scarcely believe Prussia would be so foolish to take him on in a straight fight with hardly any allies at hand on its side, especially since most of his Grande Armée was still in the heart of Germany close to the Prussian border. He drummed up support from his soldiers by declaring that Prussia's bellicose actions had delayed their phased withdrawal back home to France to enjoy praise for the previous year's victories. Once hostilities seemed inevitable in September 1806, Napoleon unleashed all French forces east of the Rhine, deploying the core of the Grande Armée along the frontier of southern Saxony. In a preemptive strike to catch the Prussians unaware, the Emperor had the Grande Armée march as a massive "bataillon carré" (battalion square) in three parallel columns through the Franconian Forest in southern Thuringia. Each corps would be in mutual supporting distance of each other, both within the column and laterally to the other columns (once through the difficult passage of the forest), thus allowing the Grand Armée to meet the enemy at any contingency. This strategy was adopted due to Napoleon's lack of intelligence regarding the Prussian main army's whereabouts and uncertainty over his enemy's puzzling manoeuvres in their march to face him. The reason for this stemmed mainly from the mutual mistrust within the Prussian high command that had resulted in division among the Prussian commanders over which plan of action for the war would be adopted. Despite the deficiency in pinpointing the main Prussian army's exact position, Napoleon correctly surmised their probable concentration in the vicinity of Erfurt and formulated a general plan of a thrust down the Saale valley, enveloping the left flank of where he believed the Prussians were located and thus cutting off their communications and line of retreat to Berlin.