In 1936 he joined the Chabai Catholic seminary in northwest Bougainville, from where he was evacuated in 1942 before the Japanese occupation during World War II.

[1][2][3] In 1964 Lapun was elected to the first House of Assembly of Papua and New Guinea for the South Bougainville seat, and was made undersecretary for Forests.

Under an earlier proposal agreed by the Australian government and the company, the people would have received just 5 percent of the unimproved value of the land.

Lapun joined the Pangu Party, which, in 1975, would lead the first government of independent Papua New Guinea, with Michael Somare as prime minister.

Support for the secessionists increased as the result of the government wanting to remove people from their land to make way for Arawa, a new town to serve the mine, and after two civil servants from Bougainville were murdered in Goroka in the PNG highlands.

Lapun thus found himself in a contradictory position of being a leading member of the Pangu Party, which stressed national unity, and being active in the movement that wanted to secede from PNG.