Dear Bill
The pass of the Saale at Dornburg war very difficult. I traveld there myself and the Saale river at those part - causes a deep cut into the landscape, to get onto the plateau of Aploda - it is a steep narrow approach. I have to find some illustration on this.
Furhter in case I read Titeux correctly (for that I would like that maybe you would be so kind to cress check, I may make a misinterpretation) - it seems that Bernadotte first was blocked by the cavalry of Murat as well.
The alternate passage at Camburg was even much worse and re jected.