The Battle of Tài Sum was a Battle that occurred in 2564 in the city of Tài Sum of Delta Halo. The battle was not a part of any war or the Second Human-Covenant War that followed the battle, but was responsible for the Re-launch of the SPARTAN-III Program, numerous population reduction of Delta Halo, and the Death of Admiral John Robertson (first captain of the UNSC Sanctuary of Spring). It was also the first time the Delta Halo Defense Fleet was used in Battle.