Bougainville (bōˈgənvĭl, Fr. bōgăNvēlˈ) [key], volcanic island (1990 est. pop. 154,000), c.3,880 sq mi (10,050 sq km), SW Pacific, largest in the Solomon Islands chain. With Buka and smaller neighboring islands, it forms an autonomous region of Papua New Guinea. Bougainville is rugged and densely forested. There are several good harbors, with the main port at Kieta. The economy is mainly agricultural; major exports are copra, ivory nuts, green snails, cocoa, tortoise shells, and trepang. Copper mining was important until 1989 when an insurrection closed down the mine. The center of administration is at Sohano, a coral island in the Buka Passage.
The island was explored in 1768 by the French navigator Louis de Bougainville. Unlike the rest of the Solomon Islands, which became British territory, Bougainville and Buka became part of German New Guinea in 1884. Occupied by Australian forces during World War I, Bougainville was mandated to Australia by the League of Nations in 1920. During World War II the island was the last Japanese stronghold in the Solomons. It became part of Papua New Guinea in 1973, despite strong secessionist sentiment. A bloody secessionist uprising, begun in the late 1980s and sparked by copper mining, persisted through much of the 1990s; in 1998 a cease-fire, monitored by Australian-led forces, went into effect. A peace accord granting Bougainville broad autonomy and promising a referendum on independence was signed in 2001. Peacekeeping forces were replaced by a smaller transition team in 2003, a constitution was adopted in 2004, and a government was elected in 2005. The autonomous government has faced challenges from former fighters on both sides of the uprising, but negotiations have led to a number of peace agreements.