The Yuuzhan Vong War (25–29 ABY), also known as the Great War by the Yuuzhan Vong, was a near–apocalyptic war which arose when the Yuuzhan Vong, a nomadic warlike species which had long ago fled the destruction of its own galaxy, invaded the galaxy. After several decades of preparations, scouting and provocations, the Yuuzhan Vong entered the galaxy at a point codenamed Vector Prime and swiftly conquered much of the Outer Rim.
Chief of State Borsk Fey’lya‘s ill-prepared and inefficient New Republic government was unable to prevent the extra-galactic species from driving inexorably toward the Core. Coruscant, the galactic capital, was conquered and remade by the invaders two years after the invasion had commenced, by which time countless species had been wiped out and entire planets rendered uninhabitable.
Using advanced biotechnology in every field of life, the Yuuzhan Vong were masters of adaptation and subterfuge, as well as brute force and terror tactics. The beliefs that the invasion was divinely ordained and that the galaxy was theirs by right were reinforced by Supreme Overlord Shimrra Jamaane and the priest caste, the conduits to the gods all Yuuzhan Vong worshiped. Thus the species attacked with ferocity, their invasion stalling only once the fleet, under command of Warmaster Tsavong Lah, had overextended itself. A vendetta against Luke Skywalker’s New Jedi Order, a heretical movement brewing among the lower castes, and rumors that their long-destroyed homeworld haunted the Unknown Regions were only a few of the factors which caused the stagnation of the Yuuzhan Vong empire. After their swift advance, technological parity soon emerged between the New Republic and the Yuuzhan Vong. The Mandalorians, led by Boba Fett, joined the Yuuzhan Vong empire in its quest to conquer the galaxy; this, however, was a ruse, and the Mandalorians were actually double agents, later joining the rest of the forces defending the galaxy. Once the New Republic had recovered from the loss of its capital, the Yuuzhan Vong were dealt a disastrous defeat at Ebaq 9.
Wracked with internal tensions as it was, the Yuuzhan Vong Empire was still able to neutralize many of the threats facing it, including the Yevetha and the Ssi-ruuk, before going once more on the offensive. The New Republic, which was reformed under Alderaanian Chief of State Cal Omas into the Galactic Federation of Free Alliances, was brought to the brink of defeat, and moved toward the fatal deployment of Alpha Red, a pathogen hostile to the Yuuzhan Vong, in response to a renewed Yuuzhan Vong advance upon its temporary capital at Dac. This dangerous end to the war was averted when Zonama Sekot, a seed of the lost living homeworld of the Yuuzhan Vong, emerged over Coruscant, its arrival precipitating the final battle of the conflict. Skywalker and other leading Jedi, who had located Zonama Sekot and urged its return, defeated Shimrra Jamaane and the true master of the Yuuzhan Vong, Onimi, during the battle, while fleets of warships clashed once more in space. The Yuuzhan Vong War ended with the deaths of the Supreme Overlord and the surrender of Warmaster Nas Choka‘s armada. The resulting Sekot Accords, which stipulated disarmament and amnesty for the Yuuzhan Vong, proved deeply unpopular for many; both the Yuuzhan Vong, and the aftermath of their devastating war, played a major role in events to come.