North of the Black Gate it lay
Where Elves and Men won the day
In an age gone by it stank of death
'Til marshland gave it fetid breath
Dagorlad
NOTE: Is this riddle answer mispelled as Dagorland or should it be the proper spelling, Dagorlad?
Dagorlad is the great, treeless, open plain between the Emyn Muil and Cirith Gorgor. Dagorlad 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. (Source: The Silmarillion)
Tolkien Gateway: Dagorlad