The Central Bureau was one of two Allied signals intelligence (SIGINT) organisations in the South West Pacific area (SWPA) during World War II.

Central Bureau was attached to the headquarters of the Supreme Commander, Southwest Pacific Area, General Douglas MacArthur.

[1] The other unit was the joint Royal Australian Navy/United States Navy Fleet Radio Unit, Melbourne (FRUMEL), which reported directly to CINCPAC (Admiral Chester Nimitz) in Hawaii and the Chief of Naval Operations (Admiral Ernest King) in Washington, D.C.[1] Central Bureau is the precursor to the Defense Signals Bureau, which after a number of name changes is (from 2013) called the Australian Signals Directorate.

General MacArthur had his own signals intelligence unit, Station 6, while he was in command in the Philippines before the start of the war, and was not fully dependent on the U.S. Navy for that type of information.

General MacArthur escaped from Corregidor in the Philippines in a PT boat to Mindanao and flew to Australia from Del Monte on a Boeing B-17 Flying Fortress.

MacArthur subsequently issued orders for the formation of two complementary groups: Initially Central Bureau was made up of 50% American, 25% Australian Army and 25% RAAF personnel.

Central Bureau was a joint US-Australian signal intelligence organisation, established on 15 April 1942 under the command of US Army Major General Spencer B. Akin, with headquarters in Melbourne.Its role was to research and decrypt army and air intercept traffic and work in close co-operation with other SIGINT centres in the USA, United Kingdom and India.

It was led by Commander Eric Nave, who with Professor Dale Trendall had been working on Japanese diplomatic and naval codes at Victoria Barracks.

Central Bureau was established in a gabled, ivy-clad mansion called "Cranleigh" in Domain Road, at South Yarra, Melbourne.

He was killed when returning from a liaison visit to the wireless Experimental Centre in India, when his aircraft crashed 3 km from Calcutta airfield on 21 September 1943.

With Sinkov (US Army), the three assistant directors were Australians Alistair "Mic" Sandford (Major then Lt-Col, Second AIF) and Roy Booth (Squadron Leader then Wing Commander, RAAF).

The bureau functioned well and harmoniously, with job demarcation as Australian experience was from wireless interception and traffic analysis in the Middle East and the Americans in breaking codes and cyphers, although this "broke down" as the war went on.

[4] Experienced intercept Kana operators from a Royal Australian Air Force unit at Townsville were assigned to the new Central Bureau.

A group of cryptographic, cryptanalytic and translator personnel from the Japanese section of the Washington Signal Intelligence Service were also moved to Australia.

This RAAF Unit had started earlier in March 1942 as a small intercept station located in the initial two houses at Pimlico under Wing Commander Booth.

A message on 9 April 1942 indicated that the "RZP Campaign" against Port Moresby was to be an invasion not an air raid and which would isolate Australia from America.

MacArthur got an Australian reconnaissance plane to "discover" the Port Moresby invasion force on 5 May, leading to the Battle of the Coral Sea.

A separate American intelligence operation was located nearby in a building called "Palma Rosa" at 9 Queens Road, Hamilton.

Mic Sandford the head of the Australian Army contingent rented a house at 50 Elderney Terrace in nearby Hamilton; this became a social centre and the scene of frequent dinner and drinking parties.

The house still retained rooms with marble fireplaces, ornate plaster and 4.8m high ceilings, and the building remained the main administrative and training centre for the bureau.

These personnel, known as ASIPS, would be a liaison between Central Bureau and the Kana operators, greatly increasing the speed in which messages could be decrypted and translated.

This intercept was sent to Central Bureau at 21 Henry Street, Ascot, in Brisbane where it was decrypted and forwarded to FRUMEL where it was reportedly translated by a U.S. Navy linguist.

[23] In April and May, Central Bureau, together with analysts from FRUMEL and FRUPAC, was involved in the detection of the Take Ichi convoy, which was intending to reinforce Japanese positions in New Guinea and the Philippines.

MacArthur and General Akin summoned the Central Bureau Australian army officer Major Stan "Pappy" Clark to Manila to make contact with the Japanese.

Dufty claims that although these intercepts were "clear evidence" that prisoners had been mistreated, they could never be used in a war crimes trial without jeopardising Ultra's secrets.