These will contend for supremacy over Arda after the free peoples have been subjugated, but will work together until it happens.
The Twilight of Man (Evil), though, has two major sides in it, lead by either Sauron or Saruman. Said forces will work together until the annihilation of the evil invaders, at which point the game will end. For the Dawn of a New Age (Good), as a man of Gondor ('s various fiefs), Rohan, Vale, Dale or Dunedain (under Imladris) an elf of Mirkwood, Lothlorien or Imladris or a dwarf of Erebor or Iron Hills (under the banner of Erebor). The Last Days of The Third Age is, if not obvious enough by title alone, a modification of M&B and Warband in the setting of the heartland of the Middle Earth, during the war that will se the end of the Third Age and beginning of the Fourth.