One of the major concerns that activated Sir James Graham in the midst of the Crimean War was that the major naval threat to Britain came, not from Russia with whom the country was then at war, but from France, its temporary ally. In the 1840s French naval power and inventiveness set the pace in a new arms race. It was the French who built and launched the first screw battleship, Napoleon; during the war French naval architects invented the floating battery, which seemed to solve the old problem of conducting a safe and effective shore bombardment from warships; a great new naval base was developed at Cherbourg, facing Portsmouth and Plymouth, and implicitly challenging British control of the Channel; in 1858 the architect of the Napoleon, Stanislas Dupuy de Lôme, designed and built the first ironclad frigate, Gloire. In each case the French innovation was quickly followed by the British, who first copied the new ship, then rapidly outbuilt the French. But it was a naval arms race, with the usual characteristics of espionage, great expense and nationalism tinged with fear. The 1850s was the decade of the Crimean War, but it was also in time of repeated panics over the apparent French threat.

After a time the race died away, largely because French industry could not keep up with British production, and after 1870 the defeat by the Germans and internal instability militated against a new Anglo-French race, for French resources went into the army, aiming eventually for a war to recover Alsace and Lorraine from the new German Empire. Other Europeans entered the naval competition, so that the number of ironclads steadily increased, though they were of all sizes and all types, and spread in small numbers over many countries. But they were expensive, and only the largest and richest states could afford them, and generally only a few ships, or even only one. And only Britain and France had really sizable fleets.

France was therefore seen in Britain as the most likely enemy in a future war. After recovering from its defeat in 1854–1856, Russia developed the next largest navy after France by the 1870s, and Russia was seen as almost as likely an enemy as France. But both of these states looked even more fearfully at the developing German Empire than they did at Britain.