The Lord of the Nazgûl is disturbed by the breaking of the shadow and rides out from the city immediately. Théoden leads his Riders towards the city with Dernhelm in the leading group. Though outnumbered, they drive off the Haradrim, but out of nowhere a darkness arrives that spooks the horses. Many Riders are thrown from their saddles, including Théoden, who is crushed beneath his horse. The Lord of the Nazgûl descends on his huge, winged steed.
It becomes clear that the shadow is not only intended to cause despair among the free armies, but to protect Mordor and assist in their troops’ strength. That one side of the war relies on darkness, the other on light, is a sign that they’re fundamentally opposed and their differences become strategic touchstones in battle.
Though many of Théoden’s knights have been slain or carried away by their spooked horses, Dernhelm and Merry are alive nearby. When Dernhelm speaks to the Lord of the Nazgûl, ordering him to leave the dead, his voice sounds familiar to Merry. The Rider refuses to move and tells Dernhelm that no living man can harm him. Merry realizes that Dernhelm is really Éowyn when she takes her helmet off and shows the Black Rider that she is, in fact, a woman. As she strikes off the head of the winged beast, the shadow overhead passes away.
Mordor’s arrogance is fully embodied by the Lord of the Nazgûl, whose assurance in his immunity to challenging soldiers is based on his assumption that there are no exceptions to his prophetic strength. It’s a sign that there are more small, less obvious ways that Mordor can be defeated, partly because they’ve refused to consider the possibility that they could be defeated.
Merry feels the urge to help Éowyn and crawls towards the Lord of the Nazgûl. The Nazgûl strikes Éowyn and shatters her shield, but Merry stabs him behind the knee so that his fatal shot misses her. Éowyn uses the last of her strength to drive her sword into the Black Rider’s face. The Rider’s armor falls to the ground, seemingly empty, and a cry rises from the place where his body vanished. Merry blinks through tears to see Éowyn and Théoden lying around him unmoving.
Éowyn and Merry’s differences in appearance and status from the other Rohirrim are advantages, not weaknesses, here. The prophetic nature of their success against the Black Rider amplifies the significance of this moment—it’s a vital point in the battle between both sides and perhaps a sign that Gondor and their allies have a chance of success.
Merry goes to kiss Théoden’s hand. Théoden opens his eyes, and he tells Merry he is passing on to the land of his fathers. He asks to see Éomer before he dies, and to send word to Éowyn, who he believes to be back in Dunharrow. Merry tries to tell Théoden that Éowyn is beside him, but a clamor of trumpets sounds and he sees that the Riders are surging towards them. The horses refuse to approach the carcass of the winged beast, so Éomer dismounts to approach the king’s body. Théoden signals that the banner be given to Éomer who is now king of Rohan, and he dies in the same moment. Éomer urges the soldiers not to grieve their king, though he himself weeps as he orders the knights to bear the body away.
The fact that the Rohirrim’s horses refuse to approach the body of the Black Rider’s steed is a sign that Mordor’s animals have been bred in such oppressive captivity and such inhumane conditions that they’ve become unnatural, showing once again Mordor’s disregard for the pure strength of nature. Meanwhile, Théoden’s gracious acceptance of death shows that he feels he’s redeemed himself on the battlefield after years of being corrupted by Saruman and unable to honorably lead his people.
Éomer then recognizes Éowyn’s body. His grief spurs him to rejoin the battle and he rallies his soldiers to assail the remaining enemy forces. Merry is left behind. He sees that the sword he used to stab the Lord of the Nazgûl is smoking and soon consumed by fire. His sword-arm has gone numb. The king’s men set a fence of spears up around the fallen Rohirrim. They burn the carcass of the winged beast and dig a grave for Théoden’s horse. They carry Théoden and Éowyn into Minas Tirith; Merry walks with them.
The effect of the Lord of the Nazgûl’s terror is clearly not constrained to his own body and not ended by his death, either, which is proven by Merry’s smoking sword and his numb arm. The effects of his extreme bravery against an outsized foe begin to take their toll, which suggests it’s not enough to show bravery in one moment—that same bravery is demanded during the recovery process, too.
Rain begins to fall. Prince Imrahil rides out to greet the knights and weeps over Théoden’s body, but notices that Éowyn is still, barely, alive. He orders help be brought for her from the city before riding into battle himself. The fighting goes on, and although the Rohirrim overthrew the frontlines, they are outnumbered by the proceeding onslaught. Hope begins to disappear again—and the men on the city walls see a new threat approaching in the form of a fleet of ships arriving on the river. They proclaim this to be “the last stroke of doom.”
The other soldiers’ assumption that Éowyn had died along with Théoden is representative of the chaos of battle and the lack of careful treatment its casualties receive. This moment is another reminder of the wild oscillations of hope and despair in wartime, and that despair could easily become surrender.
The sight of the approaching ships encourages the armies of Mordor, and they fight with renewed strength. Éomer rallies his men to form a shield-wall and prepare for their last stand. But as he recites a battle verse, he sees a banner unfurling on the first ship to show the White Tree of Gondor embellished with a crown and seven stars—the sign of the king. The Rohirrim see that Aragorn and his company have arrived. They drive the enemy into Aragorn’s path. At last, Éomer and Aragorn meet on the battlefield, just as Aragorn predicted before they left Helm’s Deep. By nightfall, the enemy is defeated in Gondor, though not without huge losses.
This is a moment in which hope—namely, Aragorn’s hope that he and Éomer would meet again in battle—may seem the least logical attitude, but it is more potent than despair. Mordor’s armies’ misplaced hope in the arrival of the Black Ships shows that their fortitude comes from the reassurance that they’re larger in number than their enemy. Now that he’s begun to fulfil his role as Gondor’s true king, Aragorn’s strength is growing into a huge sign of hope for Gondor. He’s a new leader for them to rally around now that both Denethor and Faramir are absent from the battlefield.