The Koprulu Expeditionary Force was a Protoss Empire formation active before the Great War. It was commanded by Executor Tassadar. It alerted the Khalai to the zerg invasion of the Koprulu sector and was tasked by the Conclave to remove the zerg infestation from the terran worlds.
On the eve of the Great War, the force consisted of fifty Templar Caste warships led by Executor Tassadar. It encountered zerg probes on the edge of protoss space. The protoss were shocked to discover the new aliens were xel'naga-engineered, and were intent on assimilating the terrans. After a lengthy debate between the Conclave and Templar, the force was dispatched to the Koprulu sector to gather intelligence on the aliens.
The protoss were alarmed upon arriving in the Sara system. The zerg infestation of Chau Sara was well advanced and nearby terran worlds seemed likely vectors as well. The Conclave ordered the force to eradicate all traces of the infestation. Tassadar complied and burned Chau Sara, but was unsure of the morality of burning any world that was even suspected of being infested. The force set course for the infested Mar Sara.
The Terran Confederacy was caught off guard by this turn of events. Nevertheless, it prepared to defend Mar Sara, launching a clumsy counterattack against the Expeditionary Force. Struggling with his inner doubts, Tassadar could not bring himself to destroy Mar Sara nor those who had come to defend it. As such, he withdrew his forces, seeking a way to defeat the alien menace without arbitrarily wiping out humanity in the process. Aldaris relayed the Conclave's orders to destroy any terran colony which had been infested, or was even at risk of being infested. Tassadar, however, held his forces back, bombarding Mar Sara only after those on it had evacuated.
A portion of the Koprulu Expeditionary Force named 7th Fleet under Executor Andraxxus was tasked by Tassadar to stem the infestation on the terran world of Brontes IV. Initial operations against the zerg and the renegade Carpenter's Brood were successful and Andraxxus left to coordinate other operations, but the scheming of Andraxxus's adviser, Judicator Syndrea, in exterminating the terrans on the surface and in plotting the death of Demioch caused the forces of 7th Fleet on the surface to fall into infighting. Demioch and his daughter Edullon allied with the terran rebel group the New Dresdin Outlaws against Syndrea, and slew the archon Aedus/Xerxes. Zerg forces launched a counterattack on the planet, capturing Syndrea and provoking Andraxxus to rash action. After a series of victories, the swarm slew Andraxxus, all of 7th Fleet, and their New Dresdin Rebel allies.
Tassadar obeyed his orders to eradicate the zerg infestation during the pursuit to Tarsonis. However, this was done in a way to minimize human casualties, and over time the fleet's intervention became bolder. On Antiga Prime, the fleet deployed ground troops to aid the terrans on the surface, and waited for as many colonists to evacuate as possible before purifying the planet.
The zerg invaded Tarsonis en masse and here Tassadar opted not to enact purification. Instead, he committed the fleet's full strength to fight the zerg conventionally. The Confederate defenders saw just another invading alien force rather than a potential ally and engaged the protoss. The protoss also fell victim to the political aspirations of the Sons of Korhal; these terran rebels, led by Lieutenant Sarah Kerrigan, defeated the protoss at the Battle of New Gettysburg to allow the zerg to complete the destruction of the Confederacy.
In the aftermath of the Fall of Tarsonis, the Conclave ordered that Tassadar return to Aiur for punishment, humiliation and possibly execution. However, Tassadar refused to return because psionic energy drew his attention to the world of Char. The cry called for him by name, and gave him some information, such as Char being the zerg base of operations. Tassadar sent most of the fleet back home, retaining only the Gantrithor and its crew and passengers. The protoss, however, did not arrive at the planet alone, encountering Raynor's Raiders' ships as well as Alpha Squadron ships deployed by the Terran Dominion. Both of the terran fleets were under attack by the zerg and Tassadar ordered the immediate destruction of every single ship in order to prevent any infestation going further though while succeeding in this, both capital flagships, the Norad III and the Hyperion escaped, and Jim Raynor had managed to land a small number of troops on Char. Tassadar's troops were then deployed to the surface of Char to engage the zerg directly. However, the zerg ultimately prevailed against the fleet, stranding the survivors on the planet though also made a long-term alliance with Zeratul and his Dark Templar troops as well as Raynor and what remained of his Raiders. The alliance succeeded in destroying many zerg forces in battle as well as encountering Kerrigan during their stay in Char. After months of being stranded, the survivors were finally retrieved and absorbed into the Fleet of the Executor led by Artanis and Aldaris.
- Executor Tassadar (supreme commander)
- Executor Andraxxus (commander of the 7th Fleet)
- Aedus/Xerxes (archon)
- Demioch (dragoon)
- Edullon (zealot)
- Thuras (zealot)