On 27 February 1941, the War Cabinet gave official approval for the Combined Operational Intelligence Centre (COIC), Central War Room (CWR), Combined Defence Headquarters (CDH) and for Area Combined Headquarters (ACHs).  The Central War Room (CWR) and the COIC were to be manned full time from 27 February 1941.

Combined Defence Headquarters were established to provide coordinated operations to counter an enemy attack at defended ports where naval, army and air forces were based.

For trade defence operations, the naval and air forces were co-coordinated via Area Combined Headquarters (ACH). 

ACH's were established in:-

- South-Western area (Fremantle)
- South-Eastern area (Melbourne)
- North-Eastern area (initially Port Moresby, then Townsville)
- North-Western area (Darwin)

Each of these ACH's had their own COIC and a Mercantile Movements section. They were authorised to initiate trade defence operations against the enemy.


Can you help me with more information on Area Combined Headquarters?

Did they ever start to build ACH inside Castle Hill?
Was it at Sidney Street inside Castle Hill with COIC?


ACH Townsville

Proposal to relocate ACH Townsville inside Castle Hill

Central War Room (CWR)

Combined Defence Headquarters (CDH)

Combined Operational Intelligence Centres (COIC)

Bunkers, Tunnels, Fortifications in Australia during WW2

WW2 Bunkers & Fortifications in the Townsville area

Utilization of semi-underground buildings as at 2 December 1943


Can anyone help me with more information?


"Australia @ War" WWII Research Products

I need your help


 Peter Dunn 2015


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This page first produced 6 October 2000

This page last updated 17 January 2020