Battlegroup Stalingrad was a nine-ship United Nations Space Command naval Battle Group commanded by Admiral Carl "Buster" Patterson. In 2552, it was deployed to Onyx to retrieve Dr. Halsey, a joint unit of SPARTAN-IIs and SPARTAN-IIIs, and (supposedly) examples of Forerunner technologies that had been excavated. However, before it could carry out this task, it was engaged and eventually defeated by a superior Covenant fleet at the Battle of Onyx. Only the UNSC Dusk survived.