He was appointed to the Council of State, and received one of the most disorganized departments of the government to reconstruct.
This scion of an old historical family proved to be a very active wheel in the grand and magnificent organization which we owe to Napoleon.
The councillor of State was soon called from his particular administration to a ministry.

Created count and senator by the Emperor, he was made proconsul to two kingdoms in succession.

In 1806, when forty years of age, he married the sister of the ci-devant Marquis de Ronquerolles, the widow at twenty of Gaubert, one of the most illustrious of the Republican generals, who left her his whole property.
This marriage, a suitable one in point of rank, doubled the already considerable fortune of the Comte de Serizy, who became through his wife the brother-in-law of the ci-devant Marquis de Rouvre, made count and chamberlain by the Emperor.
In 1814, weary with constant toil, the Comte de Serizy, whose shattered health required rest, resigned all his posts, left the department at the head of which the Emperor had placed him, and came to Paris, where Napoleon was compelled by the evidence of his eyes to admit that the count's illness was a valid excuse, though at first that _unfatiguable_ master, who gave no heed to the fatigue of others, was disposed to consider Monsieur de Serizy's action as a defection.

Though the senator was never in disgrace, he was supposed to have reason to complain of Napoleon.

Consequently, when the Bourbons returned, Louis XVIII., whom Monsieur de Serizy held to be his legitimate sovereign, treated the senator, now a peer of France, with the utmost confidence, placed him in charge of his private affairs, and appointed him one of his cabinet ministers.