Rangers of the North
The Uruk-hai made up a large part of Saruman’s army, together with the Dunlendings and other Mannish enemies of Rohan, and similar large Orcs also served as the elite troops of Mordor. They were faster than normal Orcs and could travel during the day without being weakened. They were not only faster but smarter, stronger and larger, though some were still shorter than Men. There are suggestions that the Uruk-hai were the result of crossbreeding Orcs and Men. Certainly, other creatures in Saruman’s armies, and under his command in the Shire, appear to have been hybrids, though these “half-orcs” were as tall as Men and are never described simply as Orcs, as the Uruk-hai frequently are. It is never explained exactly how Orcs were hybridized with Men, whether through cross-breeding or some form of alchemy used to infuse Orcs with mannish qualities. Treebeard openly wonders if they are Orcs that have been somehow “improved”, or Men that were corrupted with Orc-like qualities, or if they were indeed a blending of Men and Orcs, an act which Treebeard considered to be “a black evil”. Saruman’s army of Uruk-hai fought against King Théoden of Rohan and his people at Helm’s Deep.
The race of uruks, described as “black orcs of great strength”, first appeared about the year 2475 of the Third Age, when they conquered Ithilien and destroyed the city of Osgiliath. These were evidently of Sauron’s breeding, but it is not clear whether or not these uruks should be regarded as identical with the Uruk-hai, who could be a further ‘improvement’ to the race achieved by Saruman.
The Orcs and Uruks in the service of Barad-dûr, the folk of Mordor, used the symbol of the Red Eye of Sauron. The Red Eye was also painted on their shields. These Uruks of Mordor referred to Sauron as the Great Eye, and Grishnákh was their captain. They were all long-armed and crook-legged, not as tall as the Isengarder Uruks but larger than the Moria Orcs. They could see better in the dark than the Isengarders could.