Théodred led what riders he could gather to the Fords of Isen in an attempt to halt Saruman’s assault upon Rohan, and there he fought the advance troops of the great army, which was sent to take Helm’s Deep. The dismounted riders formed a great shield-wall along the fords, but were eventually beaten back with great loss. Saruman unleashed a legion of orc-men armed with axes upon the Rohirrim with the specific intent to kill Théodred, who was known to be present at the battle of the Fords. The forces of Isengard were successful in this task, as well, mortally wounding the king’s son. They would have likely taken Théodred as a prize were it not for the valor of Grimbold, who stood over the prince’s body and fought until reinforcements led by Elfhelm arrived. The Rohirrim were forced to retreat towards Hornburg, and there recover what strength was left in hope of defending that great fortress.
While the battle at the Fords of Isen was being fought, Gandalf journeyed towards Edoras with Aragorn, Legolas, and Gimli. Upon his arrival, the members of the Fellowship managed to enter Théoden’s hall and there confront Grimá. Gandalf, in a display of his new power after returning from death in Moria, broke Saruman’s hold on the king’s mind, and spoke to Théoden concerning the true happenings of the past weeks, when Saruman advanced upon his lands unbeknownst to the king. Théoden freed Éomer at Gandalf’s urging, and banished Grimá, who was revealed at last to the king as an agent of Saruman. Summoning all men able to bear arms, Théoden hastily set out for the Hornburg, where he thought to make a stand against Saruman’s army. Gandalf, meanwhile, left both his companions of the Fellowship and Théoden and rode urgently to meet up with Treebeard, who led the Ents against Isengard and coordinated the attack of the Huorns upon Saruman’s forces at Helm’s Deep.
The Rohirrim under Théoden arrived at the Hornburg just before the main force of Saruman’s army, and through the night, a battle raged for possession of Helm’s Deep, the fortress that no opposing army had ever taken. Strengthened by what men had retreated from the Fords of Isen and led by Aragorn and Éomer, the Rohirrim managed to repel the hosts of Isengard for most of the night, but as dawn approached, Saruman’s secret weapon, a blasting fire, was revealed, and great holes were torn in the walls of the Hornburg. Desiring to make a final stand, Théoden rode down out of the Hornburg with the knights of his household, with Aragorn beside him, and they hewed a path through Saruman’s forces to the walls of the fortress. There, they beheld an amazing sight; a forest that had literally appeared overnight – the Huorns. Adding to the dismay of Saruman’s army at the sudden onset of the king and his men, as well as the Huorns, Gandalf reappeared, having found Erkenbrand, Lord of Westfold, and a thousand more warriors who had survived the battle at the Fords of Isen. With all three allies descending upon the orcs and Dunlendings, Saruman’s forces surrendered or were killed, and Rohan gained a hard-fought victory.