Copper Refinery's historic link to World War II RAAF signals intelligence operations

This year marks the 75th anniversary of Victory in the Pacific, when Japan surrendered unconditionally to the Allied forces, signalling the end of World War II.

Did you know in March 1942, at the height of World War II, a large secret bomb-proof bunker was built where the Townsville Copper Refinery stands today?

The bunker was built to shelter highly skilled katakana (kana) wireless operators who provided essential intelligence in the lead up to Victory in the Pacific (kana is a radio telegraphy code based on Japanese writing symbols).

Through analysis and cryptanalysis (kana code breaking), the kana wireless operators intercepted Japanese messages to derive critical intelligence informing the Allies when and where the Japanese were about to strike.

As part of the Townsville Copper Refinery's 50-year celebrations in 2009, the bunker's location on the current Tankhouse northern roadway was commemorated and the site was identified with a plaque.

The 21 square metre bunker with walls of solid, metre-thick, reinforced concrete was camouflaged to resemble a Queensland style farmhouse. The outside bunker walls were painted to imitate windows, doors, and even a verandah and stilt posts. The concrete structure was topped with a false roof while rainwater tanks adorned the outside and a set of stairs led up to the painted on faux front door.

Even from as close as six metres, it was difficult to determine if the windows and doors were real. Aerials and antennae were hidden among the few remaining eucalypt trees and it would have been impossible for enemy air reconnaissance to identify the building as anything other than a regular farmhouse.

Contrary to the exterior, the fully air-conditioned interior, a luxury at that time, was a highly functioning set-up complete with sophisticated equipment such as plotting and cipher tables, maps, typewriters, telephones, radio receivers and the very latest teleprinters, which were used to help decipher Japanese wireless intelligence codes that would inform Allied military forces.

After the war, the bunker was demolished in 1957 to make way for the construction of the Townsville Copper Refinery. There was no doubt it was built to last, given the amount of gelignite it took to bring it down—some kilometres away, the force of the explosion blew cracks in the outer walls of Townsville's Stuart Creek prison.

The bunker was the headquarters of No. 1 Wireless Unit, which incorporated a series of RAAF units throughout the south-west Pacific area and directly hooked up to the Central Bureau in Brisbane, one of two highly secret Allied Sigint (signal intelligence) organisations in the region.