'Vocalist' was the US geographical rather than operational codename, in succession to 'Bequest', for Yap island in the Caroline islands group of the central Pacific (1941/45).
Yap lies 93 miles (150 km) to the west-south-west of Ulithi atoll and 350 miles (565 km) to the north-east of the Palau islands group, and is a rugged, hilly island of irregular shape actually comprising four nearly-joined islands separated by very narrow and shallow channels: these are Yap, which is the largest of the four; Tomil-Gagil off Yap’s north-eastern shore; Map to the north of Tomil-Gagil; and Rumug to the north-west of Map. The island is 21 miles (34 km) long on its north-east/south-west main axis and 11 miles (17.75 km) wide across its centre, and possessed a land area of 38.7 sq miles (100 km˛). The highest elevation on the south-western portion is 585 ft (178 m) and on the north-east portion 261 ft (80 km).
The island is densely covered with coconut, areca palm and bamboo, and fruits and vegetables are grown on what is essentially a very fertile island. There were many villages around the coast, which is edged by a wide barrier reef. Located on the south-east central coast on Tomil Harbour, Yap Town was the administrative centre for the Japanese Mandated Territory’s West Carolines District, and much of the coast was edged by an paved road system.
Yap was defended by the eight battalions of Colonel Daihachi Eto’s 49th Independent Mixed Brigade with 4,423 men, the 46th Base Force with 1,494 naval personnel, and 1,000 labourers. Yap airfield was located near the southern end of the island’s south-western portion and Gagiltomil airfield on a plateau on the southern end of the north-western portion.
The island was attacked by US carrierborne aircraft of Rear Admiral John W. Reeves’s task group on 31 March 1943, during the major raid on the Palau islands group, but the damage caused was relatively light. Yap was initially a prime target in 'Stalemate II' for Major General John R. Hodge’s XXIV Corps to assault on 5 October 1944 (J-Day), but it was then bypassed.
Its defenders therefore sat out the rest of the war and surrendered to the US Navy in September 1945.