The Battle of the Hornburg was fought at Helms Deep on March 3-4 in the year 3019 of the Third Age between Saruman's army of Dunlendings and Orcs, and the army of the Rohirrim, which included Théoden, Éomer, Aragorn, Legolas, and Gimli.

At dawn on the 4th the Riders of Rohan came out of the Hornburg, pushing the invaders back and trapping them between the Riders of Rohan, Erkenbrand's army (including Gandalf), and the Huorns of Fangorn Forest.

The Dunlendings surrendered, but the Orcs retreated into the Huorn-forest where they were killed.