Lancelot - The Grail Adventures
During the Grail Adventures, Lancelot suffered unaccustomed defeats and humiliation at arms, as well as experiencing a few visions and semivisions of his own. He had visions of the Grail and finally found the door to the chapel where the holy vessel was kept. He was prevented from entering by an angelic presence and fell into a trance which lasted for several weeks. During this time, it was made clear to him this quest was at an end and his failure was due to his love for Guenevere, which exceeded his love for God. After meeting and adventuring for a time with his son Galahad in the vessel with Amide's body, he arrived at Carbonek. Here, having resolved to amend his life of his adulterous love for Guenevere, he had a Grail vision of his own - not the full experience of Galahad and his companions, but one which put Lancelot into a swoon for nearly a month, from which he awakened filled with the ineffable marvels he had seen.
Returning from the Grail Quest, however, Lancelot soon relapsed into his old love, but became more careless about secresy. Then followed more stormy episodes between the lovers, including the incident of the poisoning of Sir Patrice of Ireland and the passion and death of Elaine of Astolat. Eventually trapped alone with Guenevere by Agravaine and Mordred, Lancelot fought his way free, leaving the Queen behind with reluctance and returning to rescue her from the stake with great slaughter of Arthur's men, including Lancelot's old favorite Gareth.
Arthur and Gawaine, who had always until now been counted one of Lancelot's dearest friends, first besieged Lancelot, his kinsmen and supporters, and Guenevere in Joyous Garde. At the Pope's invervention, Lancelot restored Guenevere to Arthur, who took her back and pardoned her, but exiled her lover. Lancelot returned to his lands in France, where he parcelled out the territories and titles among his kinsmen and followers. Arthur and Gawaine pursued Lancelot across the Channel and besieged him in Gannes. Lancelot met Gawaine in single combat, but with the utmost reluctance; as always, when Lancelot won, he refused to kill Gawaine.
When Lancelot and Guenevere were discovered together in her chamber by Mordred, just when they had decided to end their love affair, Lancelot fled and Guenevere was sentenced to burn at the stake. Lancelot returned to rescue her, accidently killing Agravaine, and Gawaine's brothers, Gaheris and Gareth in the process. War between Lancelot and Arthur ensued, but was broken off when Arthur had to return to Camelot to deal with Mordred's rebellion.