The Battle of Helm's Deep is basically a battle in J. R. R. Tolkien's epic The Lord of the Rings. The battle pitted the forces of the Wizard Saruman against the Rohirrim under King Theoden, who had taken refuge in the mountain fortress of the Hornburg at Helm's Deep. Continue reading for more.
In the movie, 10,000 of Saruman's Uruk-hai (with no orcs of other races, Dunlendings or wargs to accompany them) lay siege to the fortress, which is defended by around 300 Rohirrim (before the battle, Legolas states their strength to be "three hundred against ten thousand", but he may have meant at that time, as more were fleeing to the fortress). Soon after however, a large group of the Elves of Lorien join the defences. Elrond, at the prompting of Galadriel, sends the Elves under the command of Haldir of Lorien to reinforce the defence of the keep.
During the battle, nearly all of the Elves are killed, including Haldir. The defenders suffer heavy losses, but hold out until dawn, when Gandalf arrives with 2,000 riders led by Eomer, who finally turn the tide of the battle and send Saruman's forces into retreat. In the Extended DVD version, the Huorns make an appearance, massacring the fleeing Uruk-hai after the battle, but were absent from the theatrical cut.
[Sources 1 | 2]