Complex sentence: Bougainville was to become part of an independent Papua New Guinea, however, on 11 September 1975, in a failed bid for self-determination, Bougainville declared the Republic of the North Solomons.
Split into simpler sentences: Bougainville was to become part of an independent Papua New Guinea. However, on 11 September 1975, in a failed bid for self-determination, Bougainville declared the Republic of the North Solomons.