In 1806, the Prussians were essentially defeated even before the battle of Jena.

The operations about Heilesberg, in 1807, the advance upon Madrid, in 1808, the manoeuvres about Ratisbon, in 1809, the operations of the French in 1814, and the first part of the campaign of 1815, against vastly superior numbers, are all familiar proofs of the truth of the maxim.
Strategy may therefore be regarded as the most important, though least understood, of all the branches of the military art.[4] [Footnote 4: Strategy may be learned from didactic works or from general military histories.

There are very few good elementary works on this branch of the military art.

The general treatises of the Archduke Charles, and of General Wagner, in German, (the former has been translated into French,) are considered as the best.

The discussions of Jomini on this subject in his great work on the military art, are exceedingly valuable; also the writings of Rocquancourt, Jacquinot de Presle, and Gay de Vernon.