[1] He studied law, became a judge of the Seine Tribunal in 1806, was appointed to the Cabinet of Louis Bonaparte in 1807, and later counsel to the Court of Appeal at Paris in 1811.

A great-granddaughter, Marguerite-Séverine-Philippine Decazes (widow of Prince Jean-Pierre de Broglie), married as her second husband Captain The Hon.

Immediately after the fall of the Empire, Decazes declared himself a Royalist, and remained faithful to the Bourbons throughout the Hundred Days.

The Moderates were a minority in the Chamber of 1815, so Decazes persuaded Louis XVIII to dissolve Parliament, and accordingly the elections of October 1816 returned them with a majority.

[5] As Minister of Police, he was required to suppress the insurrections provoked by the Ultra-royalists (the White Terror); after the resignation of the 5th Duc de Richelieu, he took over the day-to-day running of the ministry, although General Dessolles remained as nominal head.

He supported a policy of industrial protection the carrying out of great public works; in that time France gained economic prosperity or expansion after a downturn, and the government increased in popularity.

It was this threat of foreign intervention, rather than the clamour of the "Ultras," which forced Louis XVIII to urge a change in electoral law to prevent such a "scandal" as Grégoire's election in the future.

[2] General Dessolles and Baron Louis, refusing to embark on this policy, then resigned; thus Decazes became the new head of government, as president of the council (November 1819).

"They will attack", he proclaimed, "not your system, my dear son, but mine"; but in the end, he was forced to yield to the importunity of his family (17 February).