'Aphorism' was a US unrealised plan for the capture of Japanese-occupied Nauru island at about the same time as 'Galvanic' to take Tarawa atoll in the Gilbert islands group (15 November 1943).

Nauru is very remote, but by 1941 had become a rich phosphate mining centre under Australian control. The island has an area of only 8.1 sq miles (21 km²), and is located some 390 miles (630 km) to the west of the Gilbert islands group and 155 miles (250 km) to the north-west of Ocean island. The island’s terrain comprises a narrow coastal plain some 150 to 300 yards (140 to 275 m) wide backed by 100-ft (30-m) cliffs rising to the central plateau, whose maximum elevation is 213 ft (65 m). It was this terrain which made the island an ideal nesting site for millions of seabirds over many thousands of years, and the birds' droppings reacted chemically with the coral cap of the island to produce phosphate rock, which had been mined since 1906 first under German and then, from 1914, under Australian control. The island is surrounded by a narrow reef with numerous coral heads exposed at low tide.

The island experiences its heaviest rainfall between November and February, and for the rest of the year the island experiences easterly winds and something of a dry season. In 1941 the island’s vegetation was restricted largely to the coastal plain as the mining operations had stripped much of the soil from the central plateau. However, there was a more heavily vegetated area around Buada Lagoon on the south-western side of the central plateau.

The phosphate was extensively mined, with production at 810,000 tons per year in 1941. The mining operations left the central plateau pitted and cratered, with the excavation going as deep as 50 ft (15 m) in some places. Because the island had no proper anchorage, the phosphate was loaded at artificial moorings constructed at the edge of the reef on the island’s western side.

In 1941 the island’s population comprised about 1,800 native persons of mixed Micronesian, Polynesian and Melanesian ancestry, as well as 1,500 indentured Chinese labourers, 50 labourers from other Pacific islands, and 170 Europeans. The native population retained land ownership and received royalties for the phosphate, but did not generally work the mines. There was a coastal road right round the island and a narrow-gauge railway connecting the mines and the moorings on the west coast.

German commerce raiders sank five Australian ships off the island on 6 December 1940, and the Japanese bombed the island on 9 December 1941. The remaining Europeans were evacuated in February 1942 and elements of the 43^rd Guard Force occupied the island on 25 August 1942 after the island had been shelled by the light cruiser Yubari, destroyers Asanagi, Oite and Yunagi, and a number of auxiliary warships before these departed to repeat the process against Ocean island. The Japanese forces had built an airfield on the southern coastal strip by March 1943. At its peak, this airfield at two runways and was protected by some 200 anti-aircraft guns of varying calibres. Following the 2^nd Marine Raider Battalion’s assault on Makin island on 17/18 August 1942, the Japanese reinforced their garrison on Nauru to a strength of about 3,700 men. About 1,200 members of the native population were forcibly relocated as forced labourers to Truk atoll of the Caroline islands group, where 463 of them died.

US bombers attacked the airfield in March 1943, preventing food supplies from reaching the island.

The USA drafted the 'Aphorism' operation to invade Nauru at the same time as Tarawa, but after they had seen a model of the island’s topography, the senior commanders cancelled 'Aphorism' in favour of the 'Kourbash' seizure of Makin island as part of 'Galvanic'.

On 4 December 1943, Vice Admiral Willis A. Lee’s force of two aircraft carriers, five battleships and 12 destroyers raided Nauru island in an attempt to catch a large force of Mitsubishi G4M 'Betty' twin-engined medium bombers which had landed here from Kwajalein island. The US attack was too late to find many targets, however, and only something in the order of eight Japanese aircraft were destroyed, at the cost of four US aircraft destroyed and damage to one destroyer.

Nauru island was liberated on 13 September 1945 when the Australian frigate Diamantina approached the island and the Japanese surrendered.