At the time the only armed steamships in the French Navy were propelled by paddle-wheels, and there was great opposition to the introduction of steam power into line-of-battle ships.

The paddle-wheel was seen to be unsuited to such large fighting vessels, and there was no confidence in the screw; while the great majority of naval officers in France, as well as in England, were averse to any decrease in sail spread.

Dupuy de Lôme had carefully studied the details of the Great Britain, which he had seen being built at Bristol, and was convinced that full steam power should be used on line-of-battle ships.

His colleagues in the Génie Maritime (naval engineering) were impressed with the same idea: and in England, about this date, the earliest screw liners — converted "block ships" — were ordered.

This action on the British part decided the French also to begin the conversion of their sailing line-of-battle ships into vessels with auxiliary steam power.

As long as he retained office, Dupuy de Lôme consistently adhered to this principle; but at the same time he showed himself ready to consider how best to meet the constantly growing demands for thicker armour, heavier guns, and higher speeds.

It is important to note, however, especially during his early enthusiasm for ironclads, that only a small proportion of the ships added to the French Navy during his time in office were built of anything but wood.

In 1860 he was made a Councilor of State, and represented the French Admiralty in Parliament; in 1861, he was appointed "inspecteur général du matériel de la Marine" (general inspector for Navy equipment).

[2] In 1870 Dupuy de Lôme devoted a large amount of time to perfecting a practical navigable balloon, and the French Government gave him great assistance in carrying out the experiments.

[4] In 1875, he was busy over a scheme for embarking a railway train at Calais, and exhibited plans of the improved harbour and models of the "bateaux porte-trains" to the Academy of Sciences in July.