Like most other striplings, he was at first enamoured with the order of things produced by the re-volution, but it soon brought excesses which he did not approve. Bar was plundered, and would have been burnt, had not young Oudinot and others formed themselves into something like a military force, and driven away the ruffian mob. In the pride attendant on this success, he resolved to become a soldier. He obtained a commission, and by his bravery, unusual even at that period, rose rapidly through the subordinate ranks to be general of division.

This officer had so distinguished himself under Hoche, Pichegru, Moreau, Massena, and Buonaparte -- on the Rhine, in Switzerland, and in Italy, that the army wondered at his not being included in the creation of marshals in 1804. He was, however, made count of the empire, and presented with one million of francs. His valour at Wagram procured him the higher title of Duke of Reggio; in 1809 he at length obtained the baton: and he commanded the 12th corps in the Russian expedition; in the course of which he received many severe wounds, which, however, did not prevent his sharing all the dangers and difficulties of the retreat.

For some time after his return to the capital, the duke remained in a languishing state; and as soon as he could venture abroad, he hastened to the theatre of war in Germany, to support the declining fortunes of his sovereign. He greatly distinguished himself at the victory of Bautzen; but his want of success in the battle against Bernadotte at Grosbeeren was so displeasing to the emperor, that he was immediately superseded by Ney. Notwithstanding this unmerited disgrace, he did not refuse to serve under that marshal; and it was probably some consolation for him, that even the bravest of the brave was soon forced to retreat at Dennewitz, before the same able commander.

The abdication of the emperor having released him from his oath of allegiance, the Duke of Reggio, who had long abhorred the despotism of Napoleon, gladly offered his services to Louis XVIII., by whom he was made colonel-general of the grenadiers, and entrusted with the important military government of Metz. When Napoleon returned again to trouble France, he continued honourably faithful to the royal cause. He would have given battle to the invader, but his troops openly declared for their old leader. During the Hundred Days he steadily resisted all the overtures of Buonaparte; never appearing at court, but passing his time at his country-seat. On the second restoration of the Bourbons he was rewarded by the chief command of the Parisian National Guard, the orders of St. Louis and of the Holy Ghost, a place among the peers of France, and a seat in the cabinet.

The last military service of Oudinot was in the invasion of Spain, under the Duke of Angouleme, in 1823; and while governor of Madrid, he exerted himself with humane activity to arrest the fanatic course of the advocates of despotism, who, with the priests at their head, were yearning for the destruction of the constitutionalists.