After Friedland came the peace of Tilsit, but even peace has its dangers. Soult, Mortier and the grave Davout were at times carried away by Oudinot's extravagant spirits, and used to amuse themselves after dinner by extinguishing the candles on the table with pistol shots. During the day the general spent his time in his favourite pursuit of riding. His horses were always thoroughbreds, and nothing stopped him once he had decided to take any particular line. So one day, while attempting to jump the ditch of a fort, instead of going round by the gate, his horse fell with him, and he broke his leg and had to be sent home. His officers and comrades gave him a farewell dinner. At dessert a pâté appeared, from which, when opened by General Rapp, a swarm of birds fluttered out, with collars of tricolour ribbon, with the inscription "To the glory of General Oudinot."
On returning home the Emperor, in addition to presenting him with the pipe of Frederick the Great, had granted him the title of count and a donation of a million francs. With part of this sum Oudinot bought the beautiful estate of Jeand Heurs. In 1808 he was selected as governor of Erfurt during the meeting of the Czar and Napoleon, and had the honour of being presented to Alexander by the Emperor, who said, "Sire, I present you the Bayard of the French army; like the 'preux chevalier,' he is without fear and without reproach." The year 1809 brought sterner interludes, and Oudinot was present in command of his grenadiers during the Five Days' Fighting, and at Aspern-Essling. On the death of Lannes he was promoted to the command of the second corps, and in that capacity played his part at Wagram. During the early part of the battle it took all his self-restraint to stand still while Davout was turning the Austrian left, but when he saw the French on the Neusiedel he could no longer control his impatience, and without waiting orders he hurled his corps against the enemy's centre, receiving in the attack two slight wounds. The next day the Emperor sent for him. "Do you know what you did yesterday?" "Sire, I hope I did not do my duty too badly." "That is just what you did—you ought to be shot." But the Emperor overlooked his impetuosity, and a week later rewarded him for his service by presenting him with his bâton, and a month later created him Duke of Reggio.
The Duke was fortunate in not being selected for duty in Spain. His next service was in 1812, when he commanded a corps on the lines of communication in Russia. This was his first independent command, and it proved that, though a good subordinate, a dashing soldier and a capable diplomatist, he did not possess the qualifications of a great general. At Polotsk the day went against the French, but when a wound caused the Marshal to hand over his command to St. Cyr, that able officer easily stemmed the Russian advance and turned defeat into victory. The Marshal, however, made up in zeal what he lacked in ability; a few weeks later, hearing that St. Cyr was wounded, he hastened back to the front. It was owing to his gallant attack on the Russians that the Emperor was able to bridge the Beresina. But, while driving off the enemy who were attempting to stem the crossing, he was again wounded. Thanks to the devotion of his staff, he was safely escorted back to France and escaped the last horrors of the retreat. In 1813 the Duke fought at Bautzen, and after the armistice of Dresden was despatched to drive back the mixed force of Swedes and Prussians who were threatening the French left under Bernadotte. The action of Grosbeeren proved once again that the Duke of Reggio had no talent for independent command, and the Emperor superseded him by Marshal Ney, whom he loyally served. Emerging unscathed from the slaughter at Leipzig, he fought with his accustomed fury all through the campaign of 1814 without adding to his reputation as a soldier. On Napoleon's abdication the Duke swore allegiance to the Bourbons, who received him with warmth, as in the early years of the revolutionary wars he had shown great humanity to the captured émigrés. Louis XVIII. nominated him colonel-general of the royal corps of grenadiers, and gave him command of the third military division, with headquarters at Metz. It was there that the Marshal first heard of the Emperor's return from Elba. He at once set out to try and intercept his advance on Paris, but his troops refused to act against their former leader. Thereon Oudinot threw up his command and returned to Jeand Heurs. On his arrival at Paris, the Emperor told his Minister of War, Davout, to summon the Duke of Reggio to court, thinking that, like many another, he would forget his oath to the Bourbons. But the Duke was of different stuff; he had sworn allegiance to Louis XVIII. at Napoleon's command, but he could not break his oath. On his arrival the Emperor greeted him with the question, "Well, Duke of Reggio, what have the Bourbons done for you more than I have done, that you attempted to intercept my return?" The Marshal replied that he had plighted his oath. The Emperor told him to break it and take service with him, recalling past favours. The Marshal was much affected, but firm. "I will serve nobody since I cannot serve you," he said, "but trust me enough not to spy on me with your police: save me that degradation. I could not endure it." So the interview ended, and the Marshal returned to Jeand Heurs.
On the second Restoration Oudinot became a great favourite of the Bourbons. The King made him a peer of France, presented him with the order of St. Louis, created him one of the four major-generals of the Royal Guard and commandant-in-chief of the National Guard. When the heir to the throne, the Duke of Berri, married a Neapolitan princess, the second wife of the Marshal became her chief lady, and the Oudinots, husband and wife, served the royal family with the greatest fidelity. The Marshal once again saw service when, in 1823, he commanded the first corps of the army which invaded Spain. It was through no fault of his that Charles X. lost his throne, for he was patriotic enough to tell him how unfortunate was the disbanding of the National Guard and his other ill-advised actions.
After the fall of the Bourbon dynasty in 1830, the Duke of Reggio never again entered public life, although in 1839 Louis Philippe created him Grand Chancellor of the Legion of Honour, and in 1842 governor of the Invalides. It was in this honoured position that the Duke breathed his last on September 13, 1847, in his eighty-first year.
The Duke of Reggio was fortunate in his career; he never saw service in Spain, and he seldom held independent command, for which his fiery temper and impetuosity unfitted him. It was his gallantry and intrepidity which won for him his bâton. In a subordinate position he could usually control himself enough to obey orders, in a subordinate position also he could do good staff work, and his quick impetuous brain teemed with ideas which were useful to his superiors. But by himself he was lost. Napoleon well knew his shortcomings. In 1805 the Emperor was holding a review; Oudinot's horse was restive and refused to march past, whereon he drew his sword and stabbed it in the neck. That evening at dinner the Emperor asked, "Is that the way you manage your horse?" "Sire," replied Oudinot, "when I cannot get obedience that is my method." But it was seldom that his impetuosity resulted in cruelty, and the wounded at Friedland and in many another action had cause to bless him. The hero of Friedland, the saviour of the émigrés, and the administrator of Neuchâtel was loved not only in the French army, but also among the enemy. At Erfurt there was a poor Saxon gardener who delighted to cultivate a rose which he called Oudinot; when asked the reason he replied, "The general has made me love the war which has ruined me." The Duke of Reggio turned his face steadily against plundering, and would reprimand any officer who recklessly rode over a field of wheat.
Old age did not change his character. Happy in his family relations, adored by his young wife, he was universally beloved, and it was with great grief that, on September 13, 1847, Royalist, Orleanist, Imperialist, and Republican learned that he whom the soldiers called "The Marshal of the Thirty-Four Wounds" had passed away.