Uruk-Hai Pikemen formed the core of the ten thousand strong army that Saruman the White sent to attck the Rohirrim's fortress of Helm's Deep. Uruk-Hai Pikemen were equiped with large pikes around 12 feet in length in order to counter the cavalry that were the main strength of the Rohirrims army. Thier armour was similar to the rest of Sarumans Uruk-Hai consisting of a steel breastplate, greaves, a helmet and gauntlets which often varied in appereance and quality due to being produced by crude orc smiths nevertheless they were one of the most heavily armed and armoured soldiers that fought for Sauron's side during the War of the Ring.

Battle of Helms Deep(Movie)

During the battle of Helms Deep most of the Uruk Pikemen present were unable to take an active part in the fighting until the Deepening Wall was breached or the main gate had battered down. Once the wall was breached the Uruk Pikemen were among the first units to become involved in hand to hand fighting taking a charge from Aragorn and the Galadrim elves skewering many of them in thier initial charge. Uruk Pikemen also fought at the main gate were one succeeded in wounding King Theoden unitl he slew it with a spear. The Pikemen along with the rest of the Uruks then pushed the remaining defenders toward the keep. 

When Eomer's forces arrived the next day to relieve the defenders the Uruk Pikeman tried to set u a pike wall in order to nullify the riders charge however the rising of the sun above the riders dazed and confused the Pikemen allowing the Rohirrim to sweep over their lines.

What remained of the Uruks were killed by Huorns as they attempted to retreat back to Isenguard.

Armed with long spears, a group of Uruk Pikemen can skewer opposing forces while charging. Pikemen will crush their enemies when huddled in a Porcupine formation, but move more slowly. In this formation, Uruk Pikemen have done terrible things to the ranks of Rohirrim. The terrible warriors of Isengard form battalions of twenty in number and rampage against anything, including Orcs.

Saruman's Army mainly consisted of Pikemen. Saruman himself, an expert of war instructed his smiths to forge long spears capable of dismounting or killing any Rohirrim.