It was not unknown for frigates and ships of the line to clash during the Age of Sail. On the 13th January 1797, two British frigates, the Indefatigable and Amazon attacked the French 74 Droits de l'Homme, damaging her, and forcing her to wreck herself. This showed the conditions frigates needed to attack larger ships. The battle was fought in rough seas, which equalised the situation by preventing the Droits de l'Homme opening her lower gunports. Indefatigable was a notably heavy frigate, having been razeed from a 64 gun ship of the line. The advantage of numbers allowed the British frigates to ensure that one was always in an advantageous position. Gunboats, carrying single heavy gun, also posed a threat to lone battleships, albeit one that could not venture far from the coast. However, for smaller craft to pose a threat to a battlefleet would have to wait until the age of steam to arise.

Some of the first ironclads could certainly be classified as 'small ships' compared to the first-rates of the time. Warrior was initially thought of as an ironclad frigate, though her armour meant she could give any contemporary first rate a run for her money. Similarly, Monitor displaced just 1000 tonnes, compared to 4000 for a contemporary British first rate, against which she certainly stood a fighting chance. However, these ships quickly supplanted the unarmoured ship of the line to become battleships in their own rights. The Royal Navy continued the gunboat tradition with the ironclad 'flat iron' or Rendel gunboats, though these were never a success against larger ships. However, at the same time, the first experiments with torpedoes were beginning. The first device commonly called a 'torpedo' was the spar torpedo. This was a large explosive charge placed on a long wooden pole, or spar. It was placed close to a target ship by a small boat (or early submarine) and detonated. The first spar torpedo attacks were carried out during the American Civil War. On the 5th October 1863, the Confederate semi-submersible spar torpedo boat David attacked the Union ironclad New Ironsides off Charleston Harbour, causing heavy damage. On the 17th February the next year, the sloop Housatonic would be sunk by the Confederate submarine H L Hunley (along with the sub herself). The Union also adopted these weapons, with the Confederate ram Albemarle being sunk on the 27th October 1864 by two steam launches. The spar torpedo was a useful weapon, but only really useful against a stationary target. This was true, though to a lesser extent, of the 1871 Harvey kite torpedo, which was towed into its target. In tests against the ironclad Royal Sovereign, the torpedo scored 10 hits out of ten against a stationary target, and six out of six against a target moving at low speeds.

At much the same time, Robert Whitehead, an engineer working for the Austrian Navy, was working on a self-propelled torpedo. There had been attempts to make such a device before, but all failed on problems with depth-keeping. Whitehead's 'secret' (a combination of a hydrostat and a pendulum) solved this handily. In 1868, he sold his torpedoes to the Austrian Navy, and a year later to the Royal Navy. Various imitators, most notably the German Schwartzkopff torpedo, soon followed. In 1872, the RN's Torpedo Committee reported on four ways to deliver torpedoes: launching chutes or tubes from major warships, from ship's boats, from specially built launches or from specially built ships. All four were swiftly tried. The RN's first purpose-built torpedo boat was the Vesuvius of 1874, a small, stealthy boat with a single tube. She was slow, and was never successful. However, she did indicate the way forward. In 1876, she was succeeded by the faster Lightning, the first true torpedo boat. The launch of Lightning marked the date when the small, fast boat posed a true threat to the battleship at sea; and hence the date when battleships had to fight back in earnest.

As an aside: Intermediate between Vesuvius and Lightning was the Polyphemus, a so-called 'torpedo ram'. As the description suggests, she had a large ram as well as her torpedo armament. She was intended to sneak her way into a hostile anchorage and sink as many ships as possible, though would have been at a disadvantage against a ship at sea.