- Jim Raynor(src)
The zerg invasion of Tarsonis, capital world of the Terran Confederacy, had shattered the Confederacy's power. During the invasion, Arcturus Mengsk of the Sons of Korhal sent Lieutenant Sarah Kerrigan to stop a protoss fleet from attacking the zerg, which would have allowed the Confederacy to flee the planet. Kerrigan was subsequently abandoned to the zerg.
Captain Jim Raynor and the Commander were angered by Mengsk's increasingly extreme methods, and the abandonment of Kerrigan was the last straw. As Mengsk began to reform the Sons of Korhal into the Terran Dominion, Raynor and the Commander defected along with a number of Sons of Korhal members, many whom had come from the Mar Sara Colonial Militia. In response, General Edmund Duke activated the Ion cannon, the primary defensive weapon of Tarsonis, to keep Raynor and his forces from leaving the planet.
Raynor and his forces destroyed the Ion cannon, securing their escape from the planet. Raynor and his men later raided the Dylarian Shipyards and stole the Hyperion, Mengsk's command ship. Using the Hyperion as their mobile base of operations, they became Raynor's Raiders, and began a guerilla war to undermine Mengsk's control of the sector.
Mengsk and Duke eventually resettled Korhal, Mengsk's homeworld that had been destroyed by the Confederacy, and founded the Terran Dominion with Mengsk crowned its Emperor. Mengsk pressed most of the Confederacy's assets into the Dominion and became ruler of much of the terran colonies in the sector.
The player's starting forces are adequate, but the player lacks for many base structures. As the player builds up their SCVs and begins mining, they should quickly build up to a factory with a machine shop, allowing them to research siege tech for their siege tanks. Mengsk's Elite Guard will primarily attack from the west with a combination of infantry, siege tanks, and goliaths, while Duke's Alpha Squadron attacks from the east with wraiths, battlecruisers, and ghosts. Duke will also use ghosts to nuke the player's base, and can do so out of detection range of missile turrets, so the player should have a comsat station ready to sweep to find the nuking ghost, and destroy it before the targeting of the nuke finishes. Vultures can lay spider mines to help deter ghosts, but normal ground units will also set off the mines, so this is not an entirely reliable method.
An expansion exists far north of the player's starting position, but if they take it they must defend it, as it is close to Duke's base and very vulnerable to attack. Bunkers, missile turrets, and several siege tanks at each choke point will be enough to defend against most attacks. Against Duke's aerial forces, however, the player should have several goliaths ready. If the player receives word of a nuclear launch, they should quickly use their comsat station to sweep the northern areas and find Duke's ghost. While Mengsk and Duke do not exclusively attack from the west and east, respectively, they usually will.
Attacking Mengsk's or Duke's bases is a waste of time and resources, so the player should focus on their main objective. The Ion cannon is far to the north-west, guarded by many missile turrets, ghosts with lockdown, and other forces. A fleet of battlecruisers (the player will only need six or eight) can break the cannon's defenses, allowing dropships to ferry ground forces in. A combination of marines, goliaths, and siege tanks, will be able to destroy the cannon's defenders and then the cannon easily. The only difficulty that may arise is ghosts with lockdown, but the player should have the numbers to press on even if a few of their forces are disabled. If not, the player can wait for lockdown to wear off and use the time to reinforce their troops.