The Third War and the birth of the Lich King as a global threat

What was the Third War?

The Third War was Azeroth's greatest conflict before WotLK. It began with the Plague of Undeath sweeping through Lordaeron and ended with the Battle of Mount Hyjal, where the energy of the World Tree was sacrificed to destroy Archimonde — and, shortly after, with Arthas ascending the Frozen Throne as Lich King.

It was no ordinary war between Horde and Alliance. It was a war of survival against the Scourge and the Burning Legion at the same time.

The main fronts of the conflict

The war took place on multiple fronts simultaneously:

Lordaeron was the first to fall. The Plague spread through the villages, the dead rose, and Arthas — by burning his ships in Northrend and taking up Frostmourne — sealed his fate and that of the kingdom.

Quel'Thalas was destroyed. Arthas marched through the lands of the high elves to resurrect the necromancer Kel'Thuzad, corrupting the Sunwell in the process. The high elves, who had existed for millennia, lost everything in days.

Kalimdor and Mount Hyjal were the final act. Thrall, Jaina, and Malfurion had to join forces — Horde, Alliance, and Night Elves — to hold off Archimonde while Malfurion destroyed him with the power of the World Tree, Nordrassil.

The fall of kingdoms and reconfiguration of factions

The Third War destroyed political structures that had existed for centuries:

• Lordaeron ceased to exist as a human realm — it became Forsaken territory
• Quel'Thalas was devastated — the survivors would become the Blood Elves of TBC
• The Alliance of Lordaeron fragmented — each kingdom began to act more independently
• Thrall's Horde settled in Kalimdor as a legitimate power

How the Lich King gained global threat power

Ner'zhul was imprisoned in the Frozen Throne by Kil'jaeden to control the Scourge from afar. But when Arthas arrived at the Throne, the two merged into a single entity.

The result was a being with:

• Magical power of Arthas — champion of Lordaeron, trained by the best
• Necromantic knowledge of Ner'zhul — orc shaman corrupted by demons
• Full control of the Scourge — an army of undead that does not tire and does not negotiate

This put him in a different category than any previous villain. He did not want conquest — he wanted the death of all life as “deliverance.”

The hook straight to WotLK

For much of Classic and TBC, the Lich King was quiet in Northrend — not out of weakness, but out of design. He was building his army, testing heroes, letting the players grow strong enough to be a worthy challenge.

The invasion that opens WotLK — with necropolises and the plague attacking the capitals — is him deciding that the time has come.

To understand the Third War is to understand why Northrend is inevitable. It's not just an expansion — it's the culmination of a story that began before WoW existed.