Sessoyne is the landscape of a turning point in King Arthur’s war against Rome. There, Arthur positions his forces to contain the Roman army, fights Emperor Lucius in person, and kills him; the emperor’s death breaks the Roman host and gives Arthur victory. The place thus marks the campaign’s shift from a dispute over tribute to the defeat of Rome’s invading power.

Setting in the Roman Campaign

After Arthur’s forces had won an earlier field and carried prisoners to Paris, a Roman senator who escaped warned Lucius that continued fighting would bring further losses. Lucius dismissed the warning and sent King Leomie ahead with a large army, intending to follow. Arthur learned of this movement and sent his own people toward Sessoyne, taking towns and castles from the Romans as the campaign advanced.

Arthur’s Deployment

As the emperor entered the valley of Sessoyne, Arthur’s banner was displayed and the Roman force found itself surrounded, with no clear route of escape. Arthur had assigned Sir Cador to command the rearguard. Sir Launcelot, Sir Bors, Sir Kay, Sir Marrok, and Sir Marhaus were to remain with Arthur’s person, while his wider host was distributed across different positions to prevent the enemy from getting away. The disposition turns the terrain into part of the military plan: Lucius must fight or yield.

The Battle and Lucius’s Death

Lucius urged the Romans to stand by Rome’s dominion, and the fighting began with both sides suffering losses. Arthur rode through the battle to encourage his knights, wielding Excalibur where the Romans pressed hardest and rescuing his men. He also killed the giant Galapas. Sir Gawaine distinguished himself by killing three admirals, while the other Knights of the Round Table fought throughout the engagement.

The battle swung between advantage and disadvantage and continued at length. Arthur finally saw Lucius fighting and rode to meet him. Lucius wounded Arthur, but Arthur struck back with Excalibur and killed the emperor. Once Lucius’s death became known, the Roman army fled; Arthur’s forces pursued it, and the narrative reports more than one hundred thousand Roman dead.

Aftermath and Significance

Arthur ordered his own dead buried according to their rank and directed that the wounded receive treatment without stint. He also had the bodies of Lucius and other prominent enemies—including the Sultan of Syria, the King of Egypt, the King of Ethiopia, seventeen further kings, and sixty Roman senators—prepared for return to Rome. Three surviving senators were charged with carrying the bodies and Arthur’s letters to the Roman authorities. The care taken over the dead follows the battlefield’s destruction with an assertion of royal control and ceremonial order.

Sessoyne is therefore more than the site of a single combat. It is where Arthur’s carefully arranged encirclement, the prowess of his leading knights, and his personal victory over Lucius combine to defeat the imperial challenge in battle. The episode makes the Roman campaign a contest for sovereignty, resolved not by the payment of tribute but by the emperor’s death and the collapse of his army.