The Battle of Yag'Dhul took place before the Yuuzhan Vong War's invasion of Coruscant.
As a prelude to the assault, Nom Anor, using a disguise as a Givin, tried to undermine the defensive capabilities of the Yag'Dhul system.
The planet was attacked by a Yuuzhan Vong invasion force aiming to utilize it as a launchpad for an assault on the Core. However, the scheme of Nom Anor was foiled by the actions of Corran Horn, Anakin Solo and Tahiri Veila. The Givin's starships mounted a defense of Yag'Dhul, despite being at a numerical disadvantage of roughly two to one. Ultimately, Yag'Dhul was spared when Yuuzhan Vong forces were redeployed as a result of the Second Battle of Sernpidal.
Despite the book's indication that only ships designed by the Givin participated in the battle, and that New Republic support was still fifteen hours away, The New Jedi Order Sourcebook depicts a significant number of ships not of Givin design joining the battle, arriving from hyperspace.