Gandalf then led Théoden, along with what remained of the Fellowship and also Éomer, with picked Riders of the Mark, to Isengard, which now lay in ruins after the attack of the Ents. There, Aragorn, Legolas and Gimli were reunited with Merry and Pippin, and Gandalf introduced Théoden to Treebeard. The group also confronted Saruman, who refused to alter his ways. Gandalf broke Saruman’s staff and cast him from the White Council as well as the Order of the Istari. Gríma attempted to throw Saruman’s Palantír at Gandalf, but missed, and in this way was a vital connection made clear between Saruman and Sauron. Pippin later looked into the Palantír, which encouraged Sauron to send his Nazgûl over the river Anduin, and the assault he had long planned against the west began to take shape. Théoden and his men rode back to Helm’s Deep with the remnant of the Fellowship, while Gandalf set out for Minas Tirith with Pippin. While on their way to the Hornburg, Théoden’s party met up with the Grey Company under Halbarad and the sons of Elrond, and eventually Aragorn would set out with his kinsmen to pass the Paths of the Dead. Théoden and Éomer, along with their growing army, rode on to Harrowdale, where the great muster of Rohan was already underway. Once at Dunharrow, an errand-rider from Gondor came to the King, begging for help on behalf of Gondor and the Steward Denethor. Théoden fulfilled the Oath of Eorl, telling the rider that he should bring six thousand warriors to defend the Mundburg.
On the road to Minas Tirith, Théoden’s army received help from Ghân-buri-Ghân, chieftain of the Drúedain, and came to Rammas Echor at dawn of March 15 of the year 3019. That day he led the Rohirrim onto the Pelennor Fields, and the host of Rohan at first overwhelmed the orc-legions of Sauron. Théoden then led his knights against the cavalry of the Haradrim as well, personally slaying their chieftain, and hewing his banner. Yet in that moment of great victory for the king, the Lord of the Nazgul descended upon Théoden and mortally wounded him. Éowyn, sister of Éomer, had ridden to war with the Rohirrim, unknown to any of the men of the Mark, and revealed herself in single combat with the Witch-king. With the aid of Merry, Éowyn slew the Witch-king, and thus won great renown among all the peoples of the west for her bravery. Théoden, as he lay dying, called Éomer, now his heir, King of the Mark, and bade him tell Éowyn farewell, not knowing that his niece had defended him from the Witch-king. His knights bore Théoden’s body out of the battle, while Éomer led the Rohirrim in their continued assault upon the Haradrim. The forces of Mordor greatly outnumbered the armies of Gondor and Rohan, however, and defeat appeared nigh, when Aragorn, returning from the Paths of the Dead, came up from the coast in the captured ships of the Corsairs, and, leading a great many warriors gathered from the southern fiefs of Gondor, helped to turn the tide of battle.