Orcs of Mordor
The Orcs of Mordor were the orc footsoldiers of Morgoth,[source?] and when he was banished from the World, they remained under the control of his lieutenant Sauron. After Sauron established himself in the Black Land of Mordor, his Orcs continued to battle with Elves and Men over many centuries.
The Orcs of Mordor were not simply gathered from the remnants of Morgoth's armies, but were also bred anew by Sauron. There were many types in the service of the Red Eye, but the largest and fiercest were the Uruk-hai, a form first seen about five hundred years before the end of the Third Age. It seems that Sauron could breed armies of Orcs with enormous speed when they were needed. According to Aragorn, for instance, it had taken just a few years for the Orcs to multiply in Mordor to the vast hordes seen in the War of the Ring.