First World War

The First World War was fought by the most churchgoing generation of the modern age, and, as Philip Jenkins has shown in detail, every belligerent nation framed it in openly religious terms. German soldiers marched under belt buckles reading Gott mit uns while court preachers proclaimed a holy German mission; British and French pulpits answered with the language of crusade and martyrdom; Russia went to war under the banners of Orthodox holy Russia. The dead of the Battle of Mons acquired guardian angels in a legend that swept Britain in 1915, apparitions and prophecies multiplied in every combatant country, and the industrial slaughter of the Western Front was read through the Book of Revelation by clergy and soldiers alike.

The war was formally a holy war on one front. In November 1914 the Ottoman sultan caliph, at Germany's urging, proclaimed jihad against the Entente powers, an attempt to raise the Muslim subjects of Britain, France and Russia that largely failed but that entangled the institution of the caliphate in the war's outcome. Within the Ottoman Empire the war years brought catastrophe to the Armenian Christians, whose deportation and mass killing from 1915 remains the war's darkest religious legacy.

Chaplains of every faith served in the trenches, Sikh, Hindu and Muslim soldiers of the Indian Army fought across Europe and the Middle East, and the war carried the religions of half the world into contact, and into graves, on a scale never seen before.

No war has redrawn the world's religious geography so quickly. The peace dissolved four empires at once. The Ottoman collapse ended the last widely recognised caliphate: the office survived the sultanate by only two years before the new Turkish republic abolished it in 1924, leaving Sunni Islam without the institution that had, at least in name, headed it for thirteen centuries, an absence that has shaped Islamic political thought ever since. The Ottoman provinces became British and French mandates, and the Balfour Declaration of 1917, folded into the Palestine mandate, set the course toward a Jewish national home, entangling the holy land's three faiths in a new political frame.

Russia's defeat and revolution delivered the world's largest Orthodox church into the hands of a state committed to atheism, opening seven decades of antireligious persecution. In defeated Germany, the collapse of the throne ended the old union of altar and crown, and out of the war's disillusion came the theology of crisis: Karl Barth's commentary on Romans, written in its shadow, broke with the liberal theology that had blessed the war and turned Protestant thought toward a God wholly other than the nations.

Among the bereaved millions the war drove a great surge of spiritualism, seances and memorial mysticism, championed publicly by figures such as Arthur Conan Doyle, while war memorials, two minutes of silence and poppies built a new civic liturgy of remembrance that the modern world still keeps each November.