From 1973 there were movements in both the southern region of Papua and the district of Bougainville that sought to secede from the emerging state. The Papuan nationalist movement soon faded; it lacked cohesive support, and the well-educated local elite was deeply involved in government and commerce. The most dramatic challenge to the Papua New Guinea state emerged on Bougainville, site of an important copper and gold mine at Panguna. Australia had established the mine in order to lower the new state’s dependence on foreign aid. After arguments about the level of their funding, the leaders of Bougainville declared their province independent as the Republic of the North Solomons on September 1, 1975, but then rejoined Papua New Guinea in early 1976. 

The dispute, which continued for nearly a year after Bougainville reverted to the state, was finally settled—for a time—by the national government’s agreement to decentralize provincial governments and devolve some national powers. Secessionist activities on Bougainville then remained dormant until 1989. (The ideas of separation and secession, however, were not confined to Bougainville and continued to simmer on East New Britain into the 21st century, along with calls for increased autonomy by New Ireland province. These relatively developed provinces argued that they received little from the national government, deserved more revenue from present and future mining projects, and wanted to plan their own educational systems, infrastructure, and economies.)

and wanted to plan their own educational systems, infrastructure, and economies.)

Conflict was rekindled on Bougainville beginning in late 1988, when a number of disputes arose over environmental damage caused by mining, perceptions of racism in the mining industry, the large numbers of mainlanders on the island, and the distribution of mineral revenues among landowners. Militants sabotaged the Panguna mine using World War II-era explosives and weapons left behind by the Allies. 

Open warfare broke out between government and local pro-government forces and Bougainvillean factions, different groups of which sometimes fought with each other in distinct small-scale wars. In May 1990 the Bougainvillean secessionists unilaterally proclaimed independence; this declaration went unrecognized by foreign powers and was rejected by the central government, which cut off services and attempted a naval blockade.

Civil warfare continued for eight years without a clear victory on either side and at a cost of thousands of lives (estimates varied from 7,000 to 20,000); most deaths arose from lack of health care, rather than occurring outright in battle. A peace process began just after the 1997 election and was sponsored by the government of New Zealand.

 The talks took place at an army base at Burnham, New Zealand; a truce was signed there in October.

 From 1998 the Australian government provided aid as a “peace dividend” and took over the lead role in peacekeeping operations along with a United Nations and Pacific regional presence.

 Disarmament, reconciliation discussions, and peace ceremonies took place over the next decade. After years of negotiation the leaders of Bougainville and Papua New Guinea agreed in 2001 that the province of Bougainville would become an autonomous region. 

An amendment to the Papua New Guinea constitution established that a referendum on independence would be held on Bougainville within 10 to 15 years. In 2005 Bougainville voters elected their own parliament, as per an agreement made in 2003.