‘There was never a greater crime against humanity than the Fourth Crusade’ (Steven Runciman). The most controversial and debated of all the medieval crusades, the ‘Fourth’ Crusade is also the most misunderstood. Begun as another attempt to liberate Jerusalem from the Saracens. it was diverted to the city of Constantinople to free a Byzantine emperor from prison. The eventual storming and sack of the city shocked Christendom and made the schism between Latin and Greek Christianity a reality. Through illustrated lectures, using a rich range of Latin and Byzantine sources, we will explore the origins of the crusade, the logistical problems it faced, and the role of Byzantine court politics and rivalries in diverting it to Constantinople. How and why was a crusade turned against fellow Christians? Was it due to conspiracy, miscalculation or a series of very unfortunate events? Lecture style with question and answer time.