His attitude contributed greatly to give popular confidence to his cousin Louis Napoleon (Napoleon III of France), of whose coup d'état on 2 December 1851 he disapproved; but he was soon reconciled to the emperor, and accepted the title of prince.

On 9 January 1870, Prince Bonaparte wrote a letter to Henri Rochefort, the founder of La Marseillaise, claiming to uphold the good name of his family: After having outraged each of my relatives, you insult me through the pen of one of your menials.

[2]On the following day, Grousset sent Victor Noir and Ulric de Fonvielle as his seconds to fix the terms of a duel with Pierre Bonaparte.

But the prince declined the challenge, asserting his willingness to fight Rochefort, but not his "menials" (ses manœuvres).

According to Bonaparte, it was Noir who took umbrage at the epithet and struck him first, whereupon he drew his revolver and fired at his aggressor.

In the trial of Bonaparte for homicide on 21 May 1871 Théodore Grandperret served as Attorney General at the High Court convened in Tours.

[3] On 22 March 1853, Pierre married Éléonore-Justine Ruflin, the daughter of a Paris plumber working as a doorman.

Altogether, the couple had five children, but only two of them survived and reached adulthood: Pierre Bonaparte died on 7 April 1881, at the age of 65, in obscurity at Versailles.