The first one borne, the others belated.
Legions have my intentions debated.
Headdress upholding my endless mission;
I rule either way, death or submission.
Gather your might to face my attrition.
Borne the second, I'm the arm of the first.
Legions have fallen to quench my bloodthirst.
Damage I bring with the swing of my sword.
On no side I fight; no army, no horde.
Of my accord I fight: to fight all accord.
Grass and grain ruined, look on with disgust.
I'll show you fear in a handful of dust.
To bring your suffering I come in haste.
Hard, cold scales watch silently as you waste.
Now greet you the fourth, the wicked, the chased.
Hark and cower at my fearsome approach,
As the mortal realm I dauntless encroach.
Eyed in my wake is the reaper of souls.
Skin corpsely pallid, eyes dark as coals.
Scurry now mortals, and hide in your holes.
Can you identify the four characters and explain their references?