An important thing to remember is two things, of the entire Marshalate, Davout was one of the most skilled Administrators (with the exception of Berthier of course whom served as Napoleons Chief of Staff and Suchet whom created a safe and progressive region of Aragon in Spain); but also Davout was one of the most skilled commanders in the entirety of the Napoleonic Era, unique in his corps doing the impossible due to the level of extreme training that Davout would become famous for. Conversely it must be remembered that Napoleon was far from a compassionate man that trusted everyone; it was rare that Napoleon ever taught anyone how to command (with the exception of rather extensive letters to Eugene, his Viceroy in Italy whom did learn to command exceptionally well and faced larger armies in Italy at the end of Napoleons reign). He was constantly fearful of coups, particularly by skilled and popular commanders, leaving Russia and Spain to attend to political matters in Paris. With all of this, Napoleon is suspicious of this highly skilled but loyal commander.

Of all the people to assign the defense of Hamburg, Davout was the one it could have been. It's easy to be an arm chair general and look at the campaign in Germany, going poorly overall but with some victories by Napoleon until Leipzig. The campaign was more than Napoleon of course as Bernadotte had advised the Allied powers to push the Marshals away from Napoleon as a Campaign Strategy, leaving less skilled but still brave commanders like Ney and Oudinot. As such, leaving Davout in Hamburg as a bullwork against the Allies is a sound strategy but to us in the future it seems like a waste of tallent.

It is a waste of talent but it does serve a second purpose. Napoleon was weary of Davout after Jena-Auerstedt. The double battle was more than a victory, it destroyed the Prussian ability to wage war for months, allowing Napoleon little resistance as he cleared through Prussia and liberated Poland. In the introduction of Napoleon's Marshals, a collection of essays on the Marshals edited by David G. Chandler (which is one of the few sources for Davout solely), Chandler points to a quote that Napoleon made about Davout "he made mistakes at the Moskova". At Borodino, it was Davout and Murat that had to charge the Redoubt that allowed the Russian retreat at the end of the day by acting as a hard point that the French couldn't forget. With exhausted forces, Davout and Murat had to take it, and without fresh forces to peruse, the Russian army was able to escape. Now Napoleon sees Davout, loyal Davout, as someone that made a mistake. So placing Davout in Hamburg has a purpose of sending a skilled commander capable of defense but conversely putting someone he no longer had favor for away from the glory of battle. It worked against him in the end as Davout held until a French messenger had to announce to Davout the Restoration of the Bourbons, but by then it didn't matter as Davout had artfully defended Hamburg against all odds.

Yet again in 1815 it falls to armchair generals to decide where Davout was better placed. To leave Davout in Paris as Minister of War, it works to the advantage of Napoleon that his most skilled administrator would be organizing the forces of France as Berthier had died from falling off a balcony. Would Davout have been MIA on June 18th as Grouchy was? Never. Would Davout had made the numerous mistakes that Soult did as Chief of Staff? Impossible for him to live with a mistake like that. But who would have organized Frances forces? Suchet was in South East France to defend the route from Italy; Massena was retired from Napoleons service and didnt report for duty at his return, others like Marmont had fled with Louis XVIII, and the best, from Berthier to Bessiers, were dead. Napoleon needed his best at the right position. By 1815, Napoleonudt have forgiven Davout when Davout was there to meet him in Paris at his return, So the earlier fears that Napoleon had were clearly unfounded.

It was once said that when a D'vout was born, a sword jumped from its scabbard. From the moment that Davout had joined Napoleons service, he acted with extreme skill in loyalty to Napoleon. His men did the impossible, marching for thirty six hours to join the battle at Austerlitz, holding off against a full army, or taking the Great Redoubt after hours of fighting. Davout was skilled but infinitely loyal to Napoleon and supported him to the end. Little did Napoleon know that the small, balding, bespectacled man would have a legend almost as equal to him.