The introduction of the railways in the first part of the nineteenth century, and their subsequent spread over all seven continents, served as an unparalleled catalyst for both economic growth and social change. The "iron road" fostered advancements in engineering and design, made it possible for people and products to travel the globe more quickly than ever before, and was crucial to social and economic development as well as to combat. Christian Wolmar describes the emergence of modern railways in both Britain and the USA in the 1830s, and elsewhere in the following decade. He charts the surge in railway investment plans in Britain in the early 1840s and the ensuing 'railway mania' (which created the backbone of today's railway network), and the unstoppable spread of the railways across Europe, America and Asia. Above all, he assesses the global impact of a technology that, arguably, had the most transformative impact on human society of any before the coming of the Internet, and which, as it approaches two centuries of existence, continues to play a key role in human society in the 21st century.