To put it bluntly, he refused to ally with Thalor and Eldrin, refused to send troops to support the eastern front—
That alone made him the one in the wrong.
And in doing so, he'd royally pissed off both Thalor and Eldrin.
The only reason they hadn't turned on him yet, hadn't gone to war with him outright, was because they were neck-deep in the Dungeon army on the eastern front. They were stretched too thin, too tied up to make a move.
And also—because they still had other potential allies to lean on: the Behemoth clans in the south, and the Emerald Castle. That gave them a sliver of hope, just enough to keep them from going full scorched-earth.
Otherwise? They'd already be screwed.
If the roles were reversed, he wouldn't have hesitated. He'd have turned his army around in a heartbeat, stopped fighting the Dungeon forces, and marched straight for the Kingdom of the Night Elves.
If we're going down, we're taking someone with us.
