In 1915 the south-western quadrant of Ceylon was convulsed by a week of rioting in which the Buddhist Sinhalese majority attacked a Muslim minority known as the Moors. The consensus amongst historians has long been that the pogrom (as it is best described) was the spontaneous result of religious tension and/or economic grievances at the popular level, with no leadership beyond the uncoordinated activities of local agitators. The consensus ignores significant evidence of wider orchestration, including the activities of itinerant gangs and other mobile agitators, the deliberate propagation of identical false rumours throughout the affected area, and the activities of individuals and societies associated with the Sinhala-Buddhist nationalist movement. Although the picture is far from complete, the best interpretation of the evidence is that this movement orchestrated the pogrom, albeit with varying degrees of success in each locality. That it was able to do so shows that Sinhala-Buddhist nationalism (as opposed to non-communalist, Ceylon-wide nationalism) was more deeply entrenched than is usually thought, which helps to explain Sri Lanka's political direction later in the century.