The Dagorlad:

The Battle-plain. The Dagorlad was in front of the Black Gate and bordered on at least one side by the Dead Marshes, which had been creeping over the edges. At least two battles have been fought on the Dagorlad, before the War of the Ring: that of the Last Alliance in the year 3434 of the Second Age, and at least one battle with the Wainriders.