"Then can I trust in your help on Tuesday next?" asked the king.
"That I have already promised your daughter," said Lancelot. "I shall not fail. But she tells me that in your last bout you lost the field through three of King Arthur's knights, who aided the King of Northgalis, and that it is against these knights you need assistance. What knights were they?"
"They were Sir Mador de la Porte, Sir Mordred, and Sir Gahalatine. Do what we could, neither I nor my knights could make head against them."
"I would not have them know me," said Lancelot. "My plan, therefore, is this. Send me here three of your best knights, and see that they have white shields, with no device, and that I also have such a shield. Then shall we four, when the fight is well on, come out of a wood into the midst of the fray, and do what we can to defeat these champions."
This plan was carried out as Lancelot had devised. On the day fixed for the tournament he, with his three white-shielded companions, placed himself in ambush in a leafy grove near where the lists were raised. Around the field were rows of benches where the spectators might sit, and richly-adorned seats for the lords and ladies who were to adjudge the combat and award the prize of skill and valor.
Then into the lists rode the King of Northgalis, with a following of fourscore knights, and attended by the three knights of Arthur's court, who stood apart by themselves. Into the opposite side of the lists rode King Bagdemagus, with as many knights in his train.
When all were in place the signal for the onset was given, and the knights put their spears in rest and rode together with a great rush, and with such fatal fortune that twelve of the party of Bagdemagus and six of that of Northgalis were slain at the first encounter, while the knights of King Bagdemagus were driven back in disorder.
At this critical juncture Lancelot and his companions broke from their concealment and rode into the lists, forcing their horses into the thick of the press. Then Lancelot did deeds of such marvellous strength and skill that all men deeply wondered who could be the valiant knight of the white shield. For with one spear he smote down five knights, with such force that four of them broke their backs in the fall. Then turning on the King of Northgalis, he hurled him from his horse and broke his thigh.
The three knights of Arthur's court, who had not yet joined in the fray, saw this, and rode forward.