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.
On March 2, 2494, the three UNSC ships encountered the Callisto in the 26 Draconis system. The UNSC vessels 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 Lewis was killed by the explosion, along with nearly all of the bridge crew.
Following Lewis' death, then-Second Lieutenant Preston J. Cole, the only member of the bridge crew left unharmed, took command of the Las Vegas.
List of appearances