In the original history, after the Battle of Mount Hyjal ended, Arthas returned to the Northern Frontier, just as he had now. For a time, he commanded the Undead Scourge and threw the region into utter chaos. But just as he was about to seize control of the entire Northern Frontier, an unexpected development forced him to abandon the victory within his grasp and scurry back to Northrend like a fleeing hound.
When he appeared again five years later, in year 26 after the opening of the Dark Portal, Arthas had become the second Lich King!
What triggered all these changes was precisely the matter Dick was currently manipulating.
After Archimonde died at the Battle of Mount Hyjal, another Great Demon, Kil'jaeden, took full command of the invasion of Azeroth. Compared with the reckless Archimonde, Kil'jaeden was the opposite extreme. Known as the "Deceiver," he would never roll up his sleeves and enter the fray if a scheme could solve the problem.
The first person he chose was Illidan, who had gone into self-imposed exile. He revealed the location of the artifact, the Eye of Sargeras, to Illidan, then had him use this weapon, filled with an immense quantity of the Dark Titan's magical power, to bombard the Frozen Throne of Ner'zhul, the Lich King who had betrayed the Burning Legion!
Illidan complied, but the bombardment ritual, powerful enough to tear apart Northrend's continental shelf, was disrupted by Maiev, Malfurion, and Tyrande, who had come in response to a summons. This allowed the Lich King Ner'zhul to narrowly escape death. He summoned Arthas back to Northrend as quickly as possible, then merged with him.
Thus, a new Lich King was born!
The Northern Frontier, ravaged by the Undead Scourge, consequently gained a brief respite.
But right now, Dick was not