Sauron's army was the vast army of the Dark Lord Sauron. It was mustered at instances over three millenia for the sole purpose of finally defeating Sauron's mortal enemies in the West, specifically Men and their Elven allies, in both the Second and Third Ages.
Description and History
The army consisted mostly of Orcs, though it also contained Men of Harad, Variags of Khand, Easterlings from Rhun, Trolls, Half-trolls of Far Harad, Wargs, Mumakil, Black Uruks and Nazgûl mounted upon Fell beasts, and they also had naval support from the Corsairs of Umbar.
This army first substantially fought against the Last Alliance of Elves and Men at the Battle of Dagorlad and the Siege of Barad-dûr. Well into the next age, they again fought for their master throughout the War of the Ring. Notable battles fought by Sauron's army during the later War of the Ring were the Battle of Osgiliath, the Battle of the Pelennor Fields, and the Battle of the Black Gate. There were many symbols for Sauron's many garrisons. Minas Morgul's Orcs had the symbol of a wicked crescent moon, the Orcs and Uruks of Cirith Ungol and Barad-dûr bore a red eye, the others in Gorgoroth probably had just a tattered black banner with red runes. The Haradrim bore a standard of a black serpent on a scarlet field. Orcs of Barad-dûr had thick black iron, Morgul Orcs had smaller, and better-made armor (so said Samwise Gamgee) and possibly many beaked helms. Orcs of Cirith Ungol had heavier (and hulkier) chain-mail and leather aprons and belts, and possibly round or boxy helmets. No other specifics about Orcish armor are given.