The Oath of Leo III

In April 799 Pope Leo III was attacked during a procession through Rome by a group led by relatives of his predecessor, Hadrian I. He escaped and crossed the Alps to Charlemagne, king of the Franks, at Paderborn, and his enemies followed him with charges of their own. When Charlemagne came to Rome the next year, an assembly met in Saint Peter's to hear the case. On 23 December 800 the bishops declared that no one could sit in judgement on the pope, and Leo then cleared himself by a solemn oath, taken of his own free will. On Christmas Day he crowned Charlemagne.

The fresco sets the oath at an altar raised above the real window, with the clergy gathered round it, an arrangement borrowed from the Mass at Bolsena in the next room. On a scroll runs a Latin line meaning that it is for God, not men, to judge bishops. For Leo X, who had the room painted, those words were current politics. In 1516 the council he was holding at the Lateran reaffirmed that a pope answers to God alone.

Raphael left the painting of this wall to his workshop. Two painted tablets on the window lintel give the year 1517, the fourth of Leo's pontificate.