He gained fame for holding out with native Papuan soldiers in mountainous interior of Western New Guinea against overwhelming Japanese forces, as part of Operation Oaktree, maintaining one of the last Dutch-controlled outposts in the Dutch East Indies during World War II.

Jean Victor de Bruijn, one of a family of eight children, was bom to Dutch parents with some distant Javanese ancestry at the sugar plantation of Mertojoedan, near Magelang, in Java.

From Batavia, he was appointed Assistant district officer at Saparua in the Molucca Islands, where he remained for eight month, contributing to the construction of roads in order to open up the country.

The recent discovery of the Wissel Lakes in December 1936, in the mountainous interior of the island,[3][4] had made him all the more eager, but the authorities thought him to be far too young for the responsible nature of the work.

Dutch and Australian governments considered evacuating the post, but De Bruijn was determined to stay there and fight the Japanese as well as gather intelligence, in what would be called Operation Oaktree.

[12] When he came back to the highlands, he found out that with the absence of authority caused by his departure, the natives had been convinced by the Japanese to report directly to their headquarters in Fakfak,[13] occupied since April 1942.

[19] During early 1944, he started reinforcing his band of native papuans with rifles and military training, setting up ambushes against Japanese forces in the region, killing dozens of them.

[20] At the same time reports started coming in, saying that more and more Japanese troops were moving toward the mountains, fleeing from their strongholds on the northern coast at Hollandia and Sarmi, which had been invaded by the Americans.

[1] In 1963, after the handover of Western New Guinea to Indonesia, he left the island to work as the head of the Urbanisation Research Information Centre of the South Pacific Commission in Noumea, French Caledonia.