Formed in late 1942 from the machine gun companies of several infantry battalions, the 7th Machine Gun Battalion undertook defensive duties around Port Moresby and Milne Bay during the New Guinea campaign before taking part in the defence of Wau airfield during the Battle of Wau in early 1943.

[6] Assigned at divisional level to the 6th Division, the battalion was employed initially defend the beaches around Port Moresby against a possible Japanese landing.

[8] The battalion occupied several positions around Wau and Mubo and over several months took part in several actions, and suffered casualties from disease, air attacks and indirect fire.

[9] Meanwhile, a party was maintained in Port Moresby during this time, undertaking training, defensive duties and working to improve the defences.

[9] In July and August 1943, the Wau detachment returned to Port Moresby, and having been relieved by the 6th Machine Gun Battalion they embarked for Australia.