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Guldur Orcs are a group of orcs who settled in the ancient fortress of Dol Guldur in approximately TA 2941, none of them was from the abandoned fortress, but were from Moria which mainly from Mount Gundabad.
When Azog the Defiler paid homage to the Necromancer of Dol Guldur (Sauron) made a pact in which Azog would bring the armies of the Misty Mountains to conquer the North of Middle-earth and to revive the ancient kingdom of Angmar. During the quest to reclaim Erebor from the Dragon Smaug, many of the Orcs of Dol Guldur met in the Sorcery Hill and began to forge weapons and armors to prepare for war in the east region of Rhovanion. After Gandalf was imprisoned by Sauron, all the Dol Guldur Orcs departed for the Lonely Mountain. During the Battle of Five Armies, Azog lead a Legion of Dol Guldur Orcs, fortunately the orcs were defeated and annihilated in this battle, though with leaving the forces of good with terrible losses as well. ( the battle would have been won if Thorin did not charge and rally his comrades.)
These Orcs were even taller than the famous Uruk-Hai but they were still hunchbacked a little bit, they were almost identical with other Guldur Orcs and very disciplined when in their formation. They carried unusually small but long strapped shields and also wielded glaives long as pikes and used them for some reason with one hand. Their armour was only plate and high quality, though there were a lot of open areas left to make it moveable, that can explain why they are quite agile while they weak such thick armor. They had helmets similar of Saruman's Uruk-Hai but brighter in colour and the wedges were placed differently, these wedge reinforced helmets could withstand strike coming vertically and absorb the shock less, although some of them had Goblin helms of Moria Goblins from Fellowship of the Ring. They also had secondary weapons, they wielded war cleavers, instead of scimitars or swords.
Their officers had horizontal wedges on top of their helmets and carried two polearms, a war billhook and a shortened version of their infantry's glaives.