Great War: protoss against zerg over Aiur

The Great War, also called the First Contact War, was the first open conflict between the protoss and the zerg, the two ancient creations of the xel'naga, with the terrans of the Koprulu Sector caught in between. It began with the zerg infestation of terran fringe worlds and the protoss purification campaign that followed, and it ended over Aiur with the destruction of the Overmind. Across its course the Terran Confederacy fell, the Terran Dominion of Arcturus Mengsk rose in its place, and the ghost Sarah Kerrigan was transformed into the Queen of Blades. (StarCraft; StarCraft: Brood War)

Ancient Origins#

Millennia before the war, the renegade xel'naga Amon uplifted the protoss on Aiur, prizing their purity of form, and pushed the evolution of the zerg on the ash world of Zerus, prizing their purity of essence. To keep the zerg from fracturing as the protoss had during the Aeon of Strife, Amon created the Overmind as the embodiment of their collective sentience and bound it with a directive to destroy and assimilate the protoss. When the xel'naga who opposed Amon came to Zerus, he unleashed the Swarm against them; the Overmind absorbed many of the fallen and learned their secrets. Amon himself was struck down and banished to the Void, but the Overmind could not break free of his directive. Fearing that assimilating the protoss outright would breed a hybrid that would enslave the zerg, the Overmind sought a species of sufficient psionic potential to bridge the gap, and in time it found humanity. (StarCraft; StarCraft II: Wings of Liberty; StarCraft II: Heart of the Swarm; StarCraft II: Legacy of the Void)

Prelude in the Sara System#

The strongest terran power was the Terran Confederacy, ruled from Tarsonis by the corrupt Old Families. Its mistreatment of the colonies bred rebellion, the foremost being the movement led by the Mengsk family that became the Sons of Korhal under Arcturus Mengsk after the Confederacy annihilated Korhal with nuclear fire. The Confederacy secretly experimented on captured zerg and on psychics such as Sarah Kerrigan, whom Mengsk rescued. (StarCraft; StarCraft: Uprising; StarCraft: I, Mengsk)

By 2499 the Confederacy had developed psi emitters to lure the zerg into traps and turn them into a weapon. Activated in the Sara System, the emitters drew the Swarm in overwhelming numbers. The Overmind seeded Chau Sara, and Tassadar's Koprulu Expeditionary Force arrived to purify the world. Ordered to burn every colony that might be infested, Tassadar began to question his genocidal mandate and spared Mar Sara, pulling his fleet beyond terran sensors. (StarCraft; StarCraft: Liberty's Crusade)

The Fall of the Confederacy#

As the zerg spread to Mar Sara, the Confederacy abandoned its own colonists and even tried to nuke a marine platoon that had outlived its usefulness. Arcturus Mengsk exploited the collapse, rescuing Jim Raynor and rallying the Sons of Korhal. After the protoss purified Mar Sara, the rebellion gained momentum at Antiga Prime, where the defection of General Edmund Duke and Alpha Squadron proved the power of the psi emitters. (StarCraft; StarCraft: Liberty's Crusade; StarCraft: Speed of Darkness)

Mengsk then struck at the heart of Confederate power. The Sons of Korhal broke through the orbital defenses of Tarsonis and planted psi emitters across the planet, drawing the Swarm down upon the capital. In the four-way melee that followed, Mengsk ordered Kerrigan to hold the zerg hives against the protoss and then abandoned her to the Swarm, ignoring her calls for rescue over the horror of Raynor and others. The fall of Tarsonis destroyed the Confederacy. From its ruins Mengsk proclaimed the Terran Dominion, uniting the colonies under a single ruler for the first time. The zerg, their prize taken, departed for Char. (StarCraft; StarCraft: Ghost: Nova)

Char, Aiur, and the Civil War#

The Swarm carried Kerrigan to Char, where she emerged from a chrysalis as the Queen of Blades. On Char a fateful alliance formed between Jim Raynor, Tassadar, and Zeratul of the Nerazim. When Zeratul assassinated Zasz, cerebrate of the Garm Brood, he made unwitting mental contact with the Overmind, which learned the location of Aiur. The Swarm at once began the invasion of the protoss homeworld, seizing a khaydarin crystal and physically establishing the Overmind upon the planet. (StarCraft; StarCraft: Queen of Blades)

The defense of Aiur fell to Judicator Aldaris, Praetor Fenix, and the new executor Artanis. Aldaris, fearing the alliance with the Nerazim more than the zerg, moved against Tassadar, igniting a brief protoss civil war between the Conclave and the templar who stood with the exiles. Fenix and Raynor freed Tassadar from trial, and the conflict only ended when the Conclave at last admitted Tassadar had been right. (StarCraft; StarCraft: Queen of Blades)

The Death of the Overmind#

Zeratul revealed what he had learned from Zasz: the zerg were Amon's instrument, and the Overmind sought to complete the grand experiment of the perfect life form. Stopping it was vital not only for the protoss but for all living things. Fenix and Zeratul thinned the broods guarding the Overmind by assassinating its cerebrates, and Tassadar rallied his remaining forces, with Raynor's Raiders at his side, for a final assault on the hive cluster. (StarCraft)

The allied forces breached the Overmind's shell at terrible cost, but the attack faltered as the broods regrouped and the Overmind prepared to flee. Tassadar made the ultimate sacrifice, channeling the energies of the Void and the Khala through the hull of his flagship carrier, the Gantrithor, and driving it into the Overmind. The resulting pulse destroyed the Overmind before it could escape. That assault is the final mission of the original game, and the StarCraft story, told in order, follows all three of its campaigns. (StarCraft)

Aftermath#

With the Overmind dead, the leaderless Swarm ran rampant across Aiur, killing a great many of the protoss and reducing much of the planet to ash. The zerg then split into two factions, one following Sarah Kerrigan and the other the cerebrate Daggoth and a second Overmind forming on Char. Their struggle for succession would erupt into the Brood War, and the survivors of Aiur would flee to Shakuras and rebuild as the Daelaam. The full StarCraft timeline shows how quickly one war rolled into the next. (StarCraft; StarCraft: Brood War)