The self-propelled or locomotive torpedo was probably the greatest game-changer in the history of naval warfare. For the first time the largest warship could be sunk by a weapon carried by the smallest, and most navies were quick to see the potential. Although the 19th-century Royal Navy had a reputation for technological conservatism, it was an ‘early adopter’ of the torpedo and was instrumental in the development of the small fast craft that became the delivery system of choice, the steam torpedo boat. Britain’s most important contribution to torpedo warfare, however, was the invention of its antidote, the torpedo boat destroyer, or ‘destroyer’ as it came to be called. This often-told story has overshadowed the earlier but no less significant history of the torpedo boat itself in the Royal Navy, an injustice set to right by this new book.