From Halopedia, the Halo wiki
Sydney currently serves as the capital of the Unified Earth Government, the headquarters of UNSC Fleet Command, and HIGHCOM Facility Bravo-6, the headquarters of the UNSC High Command and the Security Council.
At some point, Australia replaced the union flag canton on its flag for a new national flag, featuring a large, gold Commonwealth Star on a green field — the national colors of Australia — instead.
The Unified Earth Government became a full-fledged governing entity in 2170 and gained full autonomy and authority over Earth and her colonies in 2204. As a nation on Earth, Australia has been directly subordinate to the United Nations ever since. Australia has a long history as a stable economic powerhouse. Because of this, it has become home to many UNSC military installations and technological sites. The most prominent include HIGHCOM Facility Bravo-6, where the members of the UNSC Security Council gather, and the Sydney Synthetic Intellect Institute in Sydney, as well as the ONI Beta-5 Division Ordnance Testing Facility at Swanbourne, Perth. The latter, also known as Ordnance Testing Facility B5D or the B5D Ordnance Testing Facility, oversaw the development and testing of SCOUT and RECON-class Mjolnir for the Mark V platform, and later the upgrading of the SCOUT-class Mjolnir for Mark VI (the prototype version for the Mark VI Recon armor was developed right alongside its Mark V version). Prior to this, it had also collaborated with Chalybs Defense Solutions to produce OPERATOR-class Mjolnir.
The Covenant War had been well underway for years by the time MJOLNIR Powered Assault Armor variants were being developed and tested at the B5D Ordnance Testing Facility. During the war, the UNSC supplanted the UEG's civilian government provisionally as an emergency measure. After the fall of Reach, the UNSC Security Council convened at Bravo-6 to hear what transpired from Lieutenant Wagner and to plan for the defense of Earth, its discovery by the Covenant having been deemed not only inevitable but imminent as well. UNSC Fleet Command had previously maintained headquarters in two locations: New Alexandria, Reach, and Sydney, Australia, Earth. With the utter destruction of the HQ on Reach, the one in Sydney took over as the definitive headquarters for all of FLEETCOM.
When the Covenant did finally arrive in October of 2552, Australia, was one place that came under attack. It was apparent that the Covenant understood the importance of Australia to the UNSC. The country was heavily bombarded.
Following the cessation of war with the Covenant, governing power was transferred back to the Unified Earth Government in full, at least officially. Dr. Ruth Charet was inaugurated as the new president and the primary UEG headquarters in Sydney saw this transition come to pass. As the only FLEETCOM HQ out of the two to survive the war, Sydney's Fleet Command headquarters continued to oversee all of FLEETCOM. Bravo-6 continued to serve as the headquarters for the security council and UNSC High Command, where many important decisions were made in the next few years. It was there that Kilo-Five was formed, it was there that the security council decided to launch Operation: FAR STORM, and it was there that Captain Thomas Lasky and Commander Sarah Palmer appeared after the Requiem Campaign. The Beta-5 Division Ordnance Testing Facility in Swanbourne was used as a testing site for the Materials Group's GEN2 iteration of EVA-class Mjolnir.
List of appearances