Jean-Étienne-Théodore Ducos was born in Bordeaux, France, on 22 April 1801 into a family of shipowners.

On 9 January 1851 he was Minister of Marine and Colonies, and accepted the dismissal of General Changarnier.

He and his other cabinet colleagues were forced from office that month, but he was re-appointed the day after 2 December 1851 coup.

During his administration steam boats were developed for the military, and France occupied New Caledonia.

He was responsible for organizing military transport during the Crimean War.