From Halopedia, the Halo wiki
After the UNSC Callisto was captured by Insurrectionists, the UNSC sent the UNSC Las Vegas, the UNSC Jericho, and the UNSC Buenos Aires to hunt it down. The ships' crews were completely inexperienced, and had never fired their weapons in combat before.This should have been the reason for their loss in the battle, as they had been outsmarted by the Insurrectionists' forces.
On March 2, 2494, they encountered the Callisto in the 26 Draconis System. The three UNSC ships fired six of their seven Ares Missiles, and in response, the now Insurrectionist-controlled ship maneuvered behind an asteroid, which it then detonated in the direction of the UNSC vessels using a nuclear warhead planted beforehand. The Las Vegas was seriously damaged, and Rinkishale was killed by the explosion, along with nearly all of the bridge crew.