Francis Loraine Petre hardly sounds English, but he was. His professional life was chiefly occupied by a long stint in the civil service in India. But he's best remembered now for his Napoleonic works, written after his return to Blighty. This is the first of his five books that I've read. But it moist curtainly won't be the last!
As beautiful and evocative as these larger maps are, they aren't easy to use in conjunction with the text, chiefly by dint of being hard to read. This is most especially the case with the otherwise gorgeous map of the two main battlefields, of Jena and Auerstadt.
Rather as with Austria in 1809, the Prussians, under their rather weak-willed ruler, are moved towards war by a hawkish faction, headed in part by the king's beautiful but ill-informed wife, when neither the country nor the army are ready. France on the other hand is riding high, very much in the ascendant as the victors of Austerlitz, with Napoleon at the peak of his not inconsiderable powers.
Unlike some modern writers, who feel that mind-numbing thoroughness is mandatory, where there's little of much interest to be said, Petre, very commendably, says little. This is especially true in the latter stages of this conflict. He does, however, cover all the interesting stuff with proper thoroughness, and the book remains engaging and enjoyable from start to finish. That Prussia survived this debacle is quite something!
I loved this book. It's not perfect - the hyper-detailed troop movement info, combined with difficult to read (if admittedly very beautiful) maps, is sometimes hard to follow, and the absence of front line or ground level sources makes for a notable contrast with the best of modern writing - but it's still a gripping and informative read.
 Petre's Napoleonic works are:
Napoleon's Campaign in Poland, 1806–1807
Napoleon's Conquest of Prussia 1806–1807
Napoleon & the Archduke Charles 1809
Napoleon's Last Campaign in Germany 1813
Napoleon at Bay 1814
 Bernadotte was picqued at his Corps not taking precedence over Davout's, and hung back pointedly at the outset of the campaign. Later on he made up for this lacklustre performance with a more vigorous prosecution of the pursuit of the defeated Prussians. It was his diplomatic handling of Swedsh prisoners in this campaign that would reap sch long-term dividends for the clan Benadotte, who rule Sweden to this day!