[2] The United Kingdom Government refused to ratify the annexation but in 1884 a protectorate was proclaimed over the territory, then called British New Guinea.

Portuguese and Spanish navigators sailing in the South Pacific entered New Guinea waters in the early part of the 16th century and in 1526–27, Don Jorge de Meneses came upon the principal island, which the locals called "Papua".

[7] In 1883 Sir Thomas McIlwraith, the Premier of Queensland, ordered Henry Chester (1832–1914), the police magistrate on Thursday Island, to proceed to Port Moresby and annex the eastern half of New Guinea.

At the outbreak of the First World War in 1914, Australia invaded Kaiser-Wilhelmsland on 11 September 1914 with 2000 volunteers of the Australian Naval and Military Expeditionary Force.

From July 1942, a few Australian reserve battalions, many of them very young and untrained, fought a stubborn rearguard action against the Japanese attack, over the rugged Owen Stanley Ranges.

In early September 1942 Japanese marines attacked a strategic Royal Australian Air Force base at Milne Bay, near the eastern tip of Papua.

They were beaten back by the Australian Army, and the Battle of Milne Bay was the first outright defeat of Japanese land forces during World War II.

[18] The offensives in Papua and New Guinea of 1943–44 were the single largest series of connected operations ever mounted by the Australian armed forces.

[19] The Supreme Commander of operations was the United States General Douglas Macarthur, with Australian General Thomas Blamey taking a direct role in planning, and operations being essentially directed by staff at New Guinea Force headquarters in Port Moresby.