The geography of New Caledonia (Nouvelle-Calédonie), an overseas collectivity of France located in the subregion of Melanesia, makes the continental island group unique in the southwest Pacific. Among other things, the island chain has played a role in preserving unique biological lineages from the Mesozoic. It served as a waystation in the expansion of the predecessors of the Polynesians, the Lapita culture. Under the Free French it was a vital naval base for Allied Forces during the War in the Pacific.