For thousands of years horses played a central part in the lives of people in many parts of the world. They provided mobility and played a major or dominant part in warfare. They were the main source of power other than human labour, so much so that we still measure the power of engines in horsepower. The advent of industrialisation and the steam engine, far from finishing their role, actually accentuated it, and horses became essential to nineteenth century agriculture and the life and functioning of the great modern cities of the Victorian Age. / Socially, they came to play a larger role than ever, with a passion for the turf uniting all classes of society with hunting and events the central feature of rural social life. The cavalry was still the senior arm of the British Army. By 1900 the number of horses in Britain was at an all-time high. Yet, within thirty years all of this had passed away and the horse and the entire enormous industry that had grown up around their breeding, care, use, and equipment had been reduced to a minor feature of British life. / This was a great revolution in everyday British economic and social life, yet hardly studied. Looking at it can tell us a great deal: about how different the modern world is from that of our ancestors; about the nature and impact of transformative technological and economic revolutions and their workings; and about how we can think about other, similar revolutions that are rapidly drawing upon us.