In the mid-19th century, the Orthodox Christians of the Balkans and the Middle East found themselves at the centre of a heated struggle for ascendency over the region between five empires - Russia, Britain, France, Austria, and Ottoman Turkey. This book traces the history of the international crisis over Orthodox Christendom from its origins in the 1820s-1830s to its partial resolution in the 1860s. It explains how and why the temporal powers exercised by the Orthodox clergy in the East became the focus of an escalating series of diplomatic confrontations that reached their boiling point in the 1850s with the outbreak of the Crimean War. It also shows how the resulting conflict, Europe's last great religious war, paved the way for the promulgation of reforms that British, French, and Austrian statesmen hoped would promote divisions within Orthodox Christendom and bring about the secularization of the non-Muslim communities of the Ottoman Empire.