At midnight 13-14 October, Davout and the III Corps were just west of Naumburg. Bernadotte had halted his march at 1400 on 13 October just southwest of Naumburg, so the corps were in mutually supporting distance for 14 October.

At 1630 on 13 October Davout, who was performing a personal recce towards Auerstadt, found his outposts being driven in by Prussian cavalry. That alerted him to an advance by at least a portion of the Prussian army, which Davout logically deduced.

Napoleon's order for the 14th, sent to Davout at 2200 13 October, reached Davout at 0300 14 October. He immediately gave a written copy of the order to Bernadotte. This was the order with the postscript by Berthier 'If...Bernadotte is with you, you can march together, but the Emperor hopes that he will be in the position assigned him at Dornburg.'

With contact already established with the Prussians, and indications from that contact that the Prussians were advancing in the direction of Naumburg, it is clear what the situation was and what Bernadotte should have done. Bernadotte was with Davout and should have marched with him, as going to Dornburg was now overcome by events.

And it should be noted that Davout's orders had him marching to Apolda, but that, too, was overcome by events, mainly contact with the Prussians on the afternoon of the 13th, which Bernadotte undoubtedly knew about.

Bernadotte's subsequent conduct, for whatever reason smacks of incompetence, treachery, or worse. He left Davout holding the bag and by deserting Davout was at least partially responsible for the heavy losses of III Corps on the 14th. Bernadotte had French blood on his hands.

Sincerely,
K