Immortal Army

Morgause binds Cenred's army to the Cup of Life.

“Weapons were useless against them. Th-they were men, sire, but not men. Nothing could kill them. Nothing.”

— Elyan describing Cenred's immortal army^[src]

Across history, there have been at least two immortal armies created using the magic of the Cup of Life.

A Warlord's Army

Many centuries ago, the Cup of Life fell into the possession of a great warlord. One night, he gathered his army before him and took a drop of blood from each man, collecting it in the Cup. Such was the vessel's power that the soldiers were made immortal where they stood. According to Gaius, the carnage they wrought was beyond all imagining. The army was only defeated when the Cup was emptied of the blood it contained (The Coming of Arthur).

Cenred's Army

Cenred's army, about to storm Camelot.

When the sorceress Morgause formed an alliance with King Cenred, she used him to retrieve the Cup of Life from Arthur Pendragon, who had taken it from the Druids. She then took a drop of blood from each man in Cenred's army and collected it in the Cup, a ritual which not only made them immortal but transformed them into the living dead. It also allowed her to take control of Cenred's army, and with no further need of the king, Morgause used her magic to manipulate one of his soldiers into overpowering and killing him.

Now under Morgause's command, the army marched on Camelot the following day, taking both the city and the citadel quite easily due to their new gift. Uther Pendragon and the surviving Knights of Camelot were then imprisoned in the castle dungeons, though the former was later taken to the throne room to witness Morgana (Morgause's sister and ally) crowned Queen of Camelot.

One week later, Guinevere and Sir Leon escaped from Camelot and fled to the cave that Arthur and his allies had taken refuge in. Unbeknownst to them, however, Morgana had managed to trick Gwen into drinking a potion that allowed Morgause to track them with her magic. The sorceress (accompanied by a contingent of immortal soldiers) followed their trail to the cave and appeared to have them cornered, but Arthur and his allies ultimately managed to escape when Percival and Lancelot dropped boulders from above, blocking the narrow path and halting the soldiers' pursuit. (Merlin, meanwhile, was able to take advantage of the soldiers' presence to test and confirm that the magical sword Excalibur did indeed have the power to kill the undead.)

The next day, Arthur and his new Knights infiltrated the citadel on a mission to rescue Uther. As soon as they were inside, Merlin and Lancelot split off to take care of the warning bell, and Arthur led the remaining knights to the dungeons. Arthur's group had little trouble with the immortal soldiers, locking several in a cell and easily holding their own against those that remained. However, just as the prince had managed to free his father the warning bell went off, alerting everyone in the castle to their presence. As the immortal army surrounded them, cutting off their escape route, Arthur and his allies resolved to go down fighting, and engaged the soldiers in battle.

Meanwhile, Merlin and Lancelot had abandoned their warning bell assignment in favor of finding the Cup of Life. Armed with Excalibur, the two fought their way across the castle, the sword easily destroying any immortals they came across. They arrived at the throne room with only minor injuries, and quickly dispatched the soldiers guarding the Cup. Merlin then moved to empty the Cup of the army's blood, but was stopped in his tracks by Morgause, who burst into the room and used her magic to throw him into a wall.

The blood is spilled from the Cup.

She was prevented from killing him, however, by Gaius's timely intervention. Merlin then used his own magic to throw Morgause into a pillar, seriously injuring her, before using the sword to knock the Cup of Life from its stand. The spilling of the blood immediately broke the enchantment; all over Camelot, the immortal soldiers were instantly destroyed, including those still engaged in combat with Arthur and his knights (The Coming of Arthur).