The magic horn ordeal at King Mark's court is a public test of marital fidelity whose apparent verdict turns into a source of strife. Sent by Morgan le Fay and delivered to King Mark at Sir Lamorak’s instigation, the horn is used to test Queen Isoud and a hundred other women; its result raises the threat of punishment, but the barons challenge the test’s authority and prevent the episode from becoming a straightforward judgment of guilt.

The horn and its purpose

A knight carrying a fair horn mounted with gold is on his way from Morgan le Fay to King Arthur when Sir Lamorak intercepts him. The horn is said to have a special virtue: a woman who is false to her husband will spill its drink, while a faithful woman can drink without mishap. The account identifies the device’s stated rule, but also makes clear that it is presented as a magical test, not as ordinary testimony or a formal legal proceeding.

Sir Lamorak forces the messenger to explain why he carries the horn. He then orders him to take it to King Mark and present it as a way to test the king’s lady. Sir Lamorak’s stated purpose is to affront King Mark and Sir Tristram: the challenge is directed at Mark’s marriage, but it is also expressly made in despite of Sir Tristram. Thus the ordeal enters the court already entangled in hostility between knights, rather than as a neutral inquiry.

Queen Isoud is tested

The messenger delivers the horn to King Mark and explains its supposed power. Mark makes Queen Isoud drink, along with a hundred ladies. The account reports that only four of the women drink cleanly. The narrative gives this as the horn’s outcome, but does not identify those four or independently establish the truth of the accusations implied by the result.

King Mark responds with anger and swears that Queen Isoud and the other women should be burned. The dramatic turn is from a test that claims to expose fidelity to a threat of severe punishment based on the test’s result. The episode supplies no separate evidence or hearing that would verify the horn’s verdict; its authority rests entirely on the magical property claimed for it.

The barons reject the verdict’s authority

The barons gather and state that they will not allow the women to be burned on the evidence of a horn made by sorcery. They condemn its source as well, describing Morgan le Fay as a sorceress and witch, and argue that the horn has done no good but has caused strife and debate. Their response blocks the move from apparent failure at the test to punishment: they dispute the instrument itself, not simply the severity of Mark’s proposed sentence.

Their opposition turns the ordeal into a conflict about how judgment should be made. The horn purports to make private marital fidelity publicly legible, yet the court’s response stresses that a device attributed to sorcery cannot justify condemning the women. The passage records the barons’ resistance and their hostility toward Morgan le Fay, but does not describe a final judicial ruling or a punishment carried out against the women.

Wider consequences in the court

Sir Tristram is angry with Sir Lamorak because he recognizes the horn as an act of spite against him. The ordeal therefore sharpens an existing personal rivalry while placing Queen Isoud and the other women at risk. In the same sequence, Sir Andred watches Sir Tristram’s visits to Queen Isoud; he gathers twelve knights, takes Tristram with her, and, with King Mark’s agreement, has him bound and led toward judgment at a chapel by the sea. The ordeal’s immediate political and personal atmosphere is thus one of suspicion and escalating hostility, even though the passage does not say the horn alone caused Tristram’s capture.

The horn’s consequence is less the establishment of truth than the exposure of competing claims to authority. Morgan le Fay’s device asserts that fidelity can be tested by magic; King Mark treats its result as grounds for punishment; and the barons refuse to accept that result as a sound basis for burning the women. At the same time, Sir Lamorak’s deliberate insult intensifies the conflict among the court’s knights, tying a supposed test of marriage to the rivalries surrounding Queen Isoud and Sir Tristram.