The United Kingdom of Great Britain and Ireland was a sovereign state established by the Acts of Union 1800, which merged the kingdoms of Great Britain and Ireland. The United Kingdom, having financed the European coalition that defeated France during the Napoleonic Wars, developed a large Royal Navy that enabled the British Empire to become the foremost world power for the next century. The Crimean War with Russia was a relatively small operation in a century where Britain was largely at peace with the Great Powers. Rapid industrialisation that began in the decades prior to the state's formation continued up until the mid-19th century. The Great Irish Famine, exacerbated by government inaction in the mid-19th century, led to demographic collapse in much of Ireland and increased calls for Irish land reform. The 19th century was an era of rapid economic modernisation and growth of industry, trade and finance, in which Britain largely dominated the world economy. Outward migration was heavy to the principal British overseas possessions and to the United States. The empire was expanded into most parts of Africa and much of South Asia. The Colonial Office and India Office ruled through a small number of administrators who managed the units of the empire locally, while democratic institutions began to develop. British India, by far the most important overseas possession, saw a short-lived revolt in 1857. In overseas policy, the central policy was free trade, which enabled British and Irish financiers and merchants to operate successfully in many otherwise independent countries, as in South America. London formed no permanent military alliances until the early 20th century, when it began to cooperate with Japan, France and Russia, and moved closer to the United States. Growing desire for Irish self-governance led to the Irish War of Independence, which resulted in most of Ireland seceding from the Union and forming the Irish Free State in 1922. Northern Ireland remained part of the Union, and the state was renamed to the current United Kingdom of Great Britain and Northern Ireland in 1927. The modern-day United Kingdom is the same country—a direct continuation of what remained after Ireland's secession—not an entirely new successor state.