John O'Brien (Australian Army officer)

John O'Brien (born c. 1897, died c. 1950s) was an Australian Army officer during the Second World War. He is primarily known for his service in New Guinea and his leadership role during the Kokoda Track campaign.

O'Brien joined the Australian Army prior to World War II. At the outbreak of hostilities, he served with the 39th Battalion, a militia unit largely composed of inexperienced and young soldiers. He played a significant role in the early fighting against the Japanese advance along the Kokoda Track in 1942.

His actions during the initial battles were crucial in slowing the Japanese advance, providing valuable time for reinforcements to arrive. He was known for his bravery and dedication to his men, although the desperate circumstances and overwhelming enemy force resulted in significant casualties and a difficult retreat.

Details surrounding O'Brien's entire military career and his life following the war are somewhat limited in readily available historical documentation. Records indicate he likely remained in the army for some time after the conflict, but his later career path and circumstances of his death require further research. He appears to have passed away sometime in the 1950s.

O'Brien's contributions, particularly during the Kokoda Track campaign, are remembered within the context of Australian military history as part of the broader sacrifices made during the Pacific War.