The story of (commonly known as the First War ) centers on the sudden, violent clash between the noble Human kingdom of Azeroth and the invading Orcish Horde from the world of Draenor.
: Despite their valiant efforts, the kingdom could not hold. Garona Halforcen , a half-orc spy who had gained King Llane’s trust, assassinated him, leading to the total collapse and destruction of Stormwind. The Orcish Perspective: Conquest and Victory
: Initially led by Warchief Blackhand , the Horde ravaged human settlements like Grand Hamlet and Sunny Glade.
The game concludes with the surviving humans, led by Anduin Lothar, fleeing north across the Great Sea to the kingdom of Lordaeron to seek help, which directly leads into the events of Warcraft II: Tides of Darkness .
: Khadgar (Medivh’s apprentice) and Lothar eventually discovered Medivh’s betrayal. They led an assault on his tower, Karazhan, and executed him to stop the demonic influence.
: Sargeras possessed the human sorcerer Medivh in Azeroth. Together, Medivh and Gul'dan performed a ritual to open the Dark Portal , a dimensional rift connecting their two worlds. The Human Perspective: A Kingdom Under Siege
For the Orcs, Azeroth was a new world to conquer as their own home, Draenor, was dying.
: Under Doomhammer’s leadership, the Horde successfully sacked Stormwind Keep, securing their dominance over the southern reaches of the Eastern Kingdoms. Canonical Aftermath