Morannon, known as the Black Gate, was the mighty fortified gateway believed to be built by Sauron to guard the entrance to the shadowy land of Mordor. it was a mighty gate that stretched across the Haunted Pass of Cirith Gorgor. The gates opened onto a narrow valley, Udun, and were highly defensible, only successfully assaulted once in their history by the Last Alliance. Two towers Narchost and Carchost, built on either side of the Cirith Gorgor stood as guards on Newcomers. The Plague had eliminated nearly half of the Gondorian Garrison, and the King had no possibility to replace the losses since his attentions were diverted by more pressing problems elsewhere, so Orcs could overwhelm the remaining humans and Sauron's return from the east could happen unhindered.