'Fantan' was the US geographical rather than operational codename for the Fiji islands group in the Pacific Ocean (1941/45).

Later known as 'Chervil', Fiji is a large island group in the south-western part of Polynesia, 1,300 miles (2090 km) to the north-east of New Zealand’s North Island. There are more than 250 islands in the group, of which about 80 were inhabited in 1940, with a total area of 7,056 sq miles (18274 km²). The largest islands are Viti Levu, which has most of the population, and Vanua Levu, and there are another 26 islands with areas of more than 5 sq miles (13 km²). Most of the islands are mountainous, with rugged terrain reaching to 4,000 ft (1220 m) on the two largest islands, but the coastal plains are well watered and very fertile. The islands are fringed with reefs and have a few beaches, which renders them poor targets for amphibious assault. The climate is dominated by the trade winds, the eastern coasts receiving between 100 and 120 in (250 and 300 cm) of rain per year, mostly between November and March, while the western coasts receive 65 to 70 in (165 and 178 cm) per year and are very dry between April and October. The temperature varies from 17° to 33° C (62° to 92° F), and the humidity is generally high. The islands were free of malaria and most other tropical diseases, and in the early 1940s the vegetation comprised jungle on the eastern coasts and grass and scrub on the drier western coasts.

The islands were a cultural crossroads, and the native Fijians were a mix of Melanesians, Micronesians and Polynesians. The British sought to unite the islands' various factions under a single king in August 1871 and when this failed annexed the islands as a colony on 10 October 1871. The British prohibited the sale of native land to Europeans, but brought in large numbers of Indian labourers to work the sugar fields. Small quantities of copra and rubber were also produced. By 1941 the Indians, granted equal rights with Europeans in 1937, had largely taken over the sugar industry. Gold was discovered in the northern part of Viti Levu during 1932.

in 1941 the population was about 4,300 Europeans, 104,900 native Fijians, 98,100 Indians, 2,100 Chinese, and about 11,400 persons from other parts of the Pacific or of mixed ancestry.

Significant military facilities existed when the Pacific War started, almost all of them on Viti Levu. Though its population was not large, Fiji contributed some of the most effective troops committed in the Pacific campaign, the Fijian forces reaching a peak of 8,000 men, mostly Fijians or persons of mixed Fijian and European ancestry as ethnic Indians were excluded for political reasons. About 2,500 of these troops saw combat in the Solomon islands campaign, where their exploits as scouts became legendary.