Dagorlad
The great, treeless, open plain between the Emyn Muil and Cirith Gorgor. The name means the Battle Plain in Sindarin, and refers to the Battle of Dagorlad fought there between Sauron's forces and the Last Alliance of Elves and Men at the end of the Second Age. The bodies of the dead decayed as normal, but over time part of the field became a wetland, the Dead Marshes, where the images of the fallen could be seen.
Later, in the Third Age, the Dagorlad was the site of many battles between Gondor and various Easterling armies, including the Battle of the Morannon. The countless battles of two ages left Dagorlad as a devastated wasteland, contaminated and unhealthy, with ponds of poisonous slick and mounds of scorched earth.