This was a US unrealised plan for the occupation of Ndeni island, in the Santa Cruz islands group, some 250 miles (400 km) to the east of the Solomons islands group, as an adjunct to the first part of ‘Watchtower’ (August 1942).
Ndeni is the principal island of the Santa Cruz group, and is about 25 miles (40 km) long and 14 miles (22.5 km) wide, with a total area of 195 sq miles (505.5 km²). The interior is mountainous, reaching a height of 1,801 ft (549 m), but there is a high, relatively flat plateau at the island’s western end.
The island had no facilities in 1941 and 1942, but its strategic location during the Guadalcanal campaign led the USA to attempt to build an air base on the island. The attempt was abandoned in part because of the limited resources of Vice Admiral Robert L. Ghormley’s South Pacific Area command, in part because of the island’s unfavourable terrain, and in part because the island was infested with an acute strain of cerebral malaria rendering its all but uninhabitable to Westerners.
Rear Admiral Richmond K. Turner, commander of the Amphibious Forces, Pacific Fleet, planned to use the 2nd Marines, the divisional reserve of Major General Alexander A. Vandegrift’s 1st Marine Division for ‘Watchtower’, as the Ndeni Landing Force for an assault scheduled for a date two days after the launch of ‘Watchtower’, but much of the regiment was in fact committed to reinforce Brigadier General William H. Rupertus’s Northern Landing Force involved in the ‘Ringbolt’ operation to take Tulagi, Gavutu and Tanambogo, so the regiment was therefore not detached to occupy Ndeni.
The US Navy still desired the occupation of Ndeni as late as November 1942, but the US Army deemed this unnecessary for the success of ‘Watchtower’, and also that an occupation would in any event divert troops from the main effort at a time when it was clearly impossible for the Japanese to take and hold the Santa Cruz islands group. Moreover, Ndeni was not needed as a staging base for aircraft flying from bases to the south.
The destroyer/seaplane tender McFarland operated a squadron of Consolidated PBY Catalina flying boats from the anchorage of Ndeni island until ordered to withdraw following the US tactical defeat in the naval battle of Savo Island (8/9 August 1942). The USA continued to make occasional use of Ndeni for the operation of Catalina 'boats, and these played an important reconnaissance role during the naval battles of the Eastern Solomons (24 August 1942) and Santa Cruz Islands (26 October 1942).
A US Navy seaplane tender was eventually based at Ndeni, its aircraft conducting area patrols.