'Galvanic' was the US seizure of the Gilbert islands group as the first step in the drive across the central Pacific by the forces of Admiral Chester W. Nimitz’s Pacific Ocean Areas command as a step toward the 'Cataract' seizure of the Marshall islands group in 'Flintlock' and 'Catchpole' and then the 'Forager' assault on the Mariana islands group (20/28 November 1943).

Within the Pacific theatre, the closely related campaigns for the Gilbert and Marshall islands groups, between November 1943 and February 1944, lay at the heart of the strategic campaign undertaken by Admiral Chester W. Nimitz’s Pacific Ocean Areas command and its subordinate US Marine Corps and US Army formations in the Central Pacific. The purpose of the undertakings was to take the land areas needed for the establishment of the airfields which would allow land-based air to support the later operations across the Central Pacific, and to secure vital anchorages for major naval forces. The campaign began with a costly three-day 'Longsuit' battle for the island of Betio in the Tarawa atoll, and was completed by the simpler and less costly seizures of small atolls such as Makin and Abemama.

The Japanese bases in the Gilbert and Marshall island groups constituted the key bastions of the outer perimeter of the Japanese empire’s eastern defences.

The Gilbert islands group was a British colony from which most of the Europeans had been evacuated before the Japanese arrived, but nonetheless a few Europeans had remained. Three of the atolls temporarily occupied by the Japanese 51^st Guard Force on 9 December 1941 were Butaritari (otherwise Makin), Marakei and Abaiang, and the very few Europeans found on the first of these were interned: five Europeans and 17 unarmed New Zealand coastwatchers on Beru, Tamana, Maiana, Nonouti and Kuria atolls were captured and used for forced labour. On 15 October, all 22 captives held by the Japanese were murdered, though for propaganda reasons the missionaries and nuns were not molested.

On 10 December the Japanese flew an air raid against Tarawa, the island group’s administrative centre. A second raid followed on 24 December and Japanese forces landed the same day. By the summer of 1942 the Japanese felt the islands faced little on the way of a US threat and reduced the islands' already small garrisons. The Japanese built a seaplane base on Makin and dispersed limited numbers of troops along the coasts of the atolls largely to monitor the movement of US forces in the South Pacific.

Then on 17/18 August 1942 two companies of Lieutenant Colonel Evans F. Carlson’s 2^nd Marine Raider Battalion, totalling 222 men, landed on Makin island. This is a low coral atoll some 105 miles (170 km) to the north of Tarawa. The atoll is about 18 miles (29 km) long, and its primary constituent islands are Makin (Butaritari) and Kuma. Both are long, narrow islands on the southern side of this essentially linear rather than circular atoll, with an average width of about 500 yards (460 m). Little Makin is a separate atoll just to the north of Makin. The two atolls have a combined land area of just 7 sq miles (18 km²). The atoll has a number of passes through the reef on its western side, and these required careful navigation as a result of the presence of some coral heads for ships to enter a lagoon providing a deep and spacious anchorage. Makin island is covered with coconut palms and salt brush, and has extensive mangrove swamps on the lagoon side of its western end. Much of the island’s centre was also swampy. The island is surrounded by a reef 100 to 200 yards (90 to 185 m) wide on the ocean side and 500 to 1,500 yards (460 to 1370 m) wide on the lagoon side. At high tide the lagoon-side reefs are covered with water deep enough to allow the passage of landing craft, but are fully exposed at low tide.

The atoll had been discovered in 1788 by Captain Thomas Gilbert and Captain John Marshall in the British fleet and convict transport vessels Charlotte and Scarborough, which passed Abemama, Kuria, Aranuka, Tarawa, Abaiang, Butaritari and Makin without attempting any landings. The islands became a British protectorate in 1892, ostensibly to protect the natives from exploitation by traders, and the British built their administrative centre just to the west of the centre of Makin and also constructed a road along the entire lagoon side of the island. There were four piers on the lagoon side of Makin. The population was about 1,700 Micronesians.

A small Japanese force seized Makin on 8 December 1941, expelling the natives and establishing a seaplane base.

Just before dawn on 17 August 1942, a force of 221 marines of the 2^nd Marine Raider Battalion was landed on Makin island. The raid was intended to divert Japanese attention from the 'Watchtower' landings at Guadalcanal, which had taken place 10 days earlier. Like the Guadalcanal operation, the raid was planned in great haste, but the US Navy planners correctly estimated that the Japanese garrison was weak: there were in fact only 73 men of the 62^nd Guard Force under the command of Sergeant Major Kanemitsu.

The marine raiders were transported to the atoll by the large submarines Nautilus and Argonaut, which had departed Pearl Harbor in the Hawaiian islands group on 8 August and arrived off Makin early on 16 August. The submarines spent the day reconnoitring the target by periscope, then came close ashore just before dawn to launch the marine raiders in rubber boats equipped with outboard motors. The heavy surf led to difficulty manning the boats, and Carlson decided to land all the boats at one point instead of the two landing sites originally planned. However, one boat did not get the word: 15 of the boats landed at the correct point, three others landed a short distance to the north of these, and the boat which had not heard the final orders landed 1 mile (1.6 km) to the south of the others.

Shortly after landing, one of the marine raiders fired a shot, and this alerted the Japanese garrison. Carlson therefore ordered one of his companies to rush the coastal road on the lagoon side of the islet. The marine raiders made contact with the Japanese garrison at 06.30 and began a systematic advance to the south, and in this were aided by a bombardment by the two 6-in (152-mm) guns of Nautilus, which also sank one small transport vessel and one patrol boat in the lagoon. The Japanese resisted fiercely, sniping from trees and fighting to the death around machine gun positions. During this struggle, 12 Japanese aircraft of various types bombed and strafed the island while two Kawanishi H6K 'Mavis' flying boats arrived with reinforcements: one of these was destroyed and the other driven off by machine gun fire, but not before about 35 troops had come ashore.

Late in the day, the marine raiders' advance reached the palm groves that provided excellent cover for snipers. Carlson had his men pull back into more open terrain. The Japanese responded by advancing out of cover, and were promptly bombed by their own aircraft.

Meanwhile, the 12 marine raiders whose boat had landed far to the south began rampaging through the Japanese rear, destroying the radio station and picking off Japanese soldiers. Eight of these men made it back to the submarines that evening.

Just before sunset, Carlson began a withdrawal to the landing point, but the surf was so heavy that the boats had great difficulty in clearing the reef. Only seven boats carrying fewer than 100 men made it to the waiting submarines, and Carlson and the rest of his men were forced to remain on the atoll through the night.

On the next day Carlson made another attempt to reach the submarines, but Japanese air activity prevented any more than 30 men from getting to the submarines. The Japanese later claimed that Carlson attempted to negotiate the surrender of his men at this point, but this seems out of character and in any event there were on the island few surviving Japanese to whom any surrender could have been offered. Carlson’s men swept the island during the day, collecting documents for Allied intelligence and killing the few remaining Japanese. After the fall of night, Carlson had four boats lashed to a local outrigger canoe, and this allowed him to evacuate most of his remaining men. At this time the marine raiders' losses were 19 killed, 11 missing (including the nine later captured) and 17 wounded.

Unknown to Carlson, however, nine marine raiders, mistakenly believed to have been killed in action, were left on Makin island. These men had little choice but to surrender a few days later as the Japanese reoccupied the atoll. They were taken to Kwajalein in the Marshall islands group and initially treated relatively well, but on 16 October the Japanese naval commander in the Marshall islands, Rear Admiral Koso Abe, ordered the men to be beheaded: after the war, Abe was tried for this war crime and hanged on Guam during 19 June 1947.

The raid failed to draw any significant Japanese forces away from the Solomon islands group. It is also unlikely, as has sometimes been stated, that the raid prompted the Japanese to strengthen the islands' defences to an extent greater than they had already decided as, to the Japanese, the raid was nothing more than a pinprick. However, the raid served a genuinely useful purpose inasmuch as it revealed the inadequate nature of the Pacific Fleet’s current lack of intelligence, and thus led to the establishment of a section for collecting topographic and hydrographic information, and this was of incalculable value later in the war.

In May 1943 Admiral Mineichi Koga’s Combined Fleet enacted plans for the establishment of a new outer defence line running from the Aleutian islands group, through the Marshall and Gilbert island groups to the Bismarck islands group. This new line was to be based on a series of strongly defended islands whose retention would seriously delay any US invasion force, and provide the Japanese navy with the time to organise a counterattack and, the Imperial Japanese navy believed, destroy the US invasion fleet.

The Gilbert islands group is a chain of atolls some 2,500 miles (4025 km) to the south-west of the Hawaiian islands group and just to the north of the equator. The chain comprises hundreds of islands, all of them small, with a total land area of just 166 sq miles (430 km²). The chain is about 500 miles (805 km) long and is located about 300 miles (485 km) to the south-east of the Marshall islands group and just to the north-east of the Ellice islands group. The population was quite small at about 28,000 persons, primarily Micronesian and largely Christian, and with fewer than 100 Europeans. However, the tiny land area meant the islands had the highest population density of any in the Pacific. The islanders had a high degree of self-rule, and British law prohibited land purchases by non-native persons. British oversight was exercised from Ocean island by means of a resident commissioner who also oversaw the Ellice, Phoenix, Fanning, and other small island groups in the area.

There are 16 main atolls in the chain, none of which has land to a height of much more than 12 ft (3.7 m), and these comprise coral bedrock overlaid by sand and some poor soil. These support some scrub and coconut palms. The island were relatively healthy for Westerners, with little incidence of malaria or other tropical diseases. The climate is uniformly warm and wet, with temperatures ranging from 22° to 35° C (72° to 95° F) and the annual rainfall averaging 150 to 180 in (3.8 to 4.6 m), but there are drought conditions every five to seven years, and there was a drought at the time of the 'Galvanic' invasion of November 1943.

The islands' infrastructure was limited to a lagoon-side road on each atoll and a few piers for ocean-going vessels. There were no airfields in the group before the arrival of the Japanese.

As noted above, elements of the 51^st Guard Force occupied Makin on 8 December 1941, and began to create a seaplane base and build a radio station. The nearby atolls were visited sporadically by Japanese detachments which seized Allied coast watchers and European civilians.

In November 1943, with the Ellice islands group secured as forward air bases, the Americans were prepared to strike to the north to seize the Tarawa, Makin and Abemama atolls in the Gilbert islands and Nauru island, some 185 miles (300 km) to the west, in 'Galvanic'. The seizure of the Gilbert islands group would place the US forces in a position to thrust into the Japanese Mandated Territories, in the form of the Marshall islands group to the north and the Caroline islands group to the north-east, the more so as possession of the Gilbert islands group would allow air reconnaissance missions over the Marshall islands group, which were beyond the range of aircraft operating from current US air bases.

The US Marine Corps was assigned responsibility for the assaults on Tarawa and Abemama atolls, and the US Army for the attack of Makin. During the first nine months of 1943, recruitment, training and industrial expansion was permitting a vast growth in the US forces available for Pacific operations, and in order to use these land, sea and air assets the planners of the Joint Strategic Committee (the long-range planning arm of the Joint Chiefs-of-Staff) decided not merely to reinforce the existing efforts of Admiral William F. Halsey’s South Pacific Area and General Douglas MacArthur’s South-West Pacific Area commands, but to implement a new offensive campaign through the central Pacific to offer a supplement or indeed alternative to the existing drive.

The Joint Chiefs-of-Staff therefore envisaged a five-phase grand strategic effort against Japan: in the first phase, simultaneous advances would be made by MacArthur and Nimitz, of whom the latter would have the greater resources; in the second, the Philippine islands would be recaptured; in the third, a major lodgement would be secured on the Chinese coast; in the fourth, Hong Kong would be recaptured; and in the fifth, a strategic bombing campaign would be launched against the Japanese home islands. In May 1943 the Joint Chiefs-of-Staff became the Joint War Plans Committee, and this added a sixth phase that envisaged an invasion of the Japanese home islands.

This six-phase plan was accepted by the US authorities on 8 May, and secured inter-Allied approval at the 'Trident' conference. MacArthur objected strongly to the plan, but on 20 July Nimitz was ordered to proceed with a central Pacific campaign in which the first target would not be the Marshall islands group as first envisaged, but rather the Gilbert islands group as this could be reconnoitred by the US land-based aircraft which could also support the landings.

This was to be the first time in the war that the US forces faced serious Japanese opposition to an amphibious landing. Previous landings had encountered little or even no initial resistance, but Tarawa was to be altogether different. The strategic rationale of the operation was based on the US planners' decision to establish in the Mariana islands group a number of forward air bases capable of supporting long-range operations by heavy bombers right across the mid-Pacific, the Philippine islands group, and into the Japan home islands themselves.

The Mariana islands group was heavily defended, however, and in order for any assault on them to succeed, it was believed that land-based bombers would have to be used to 'soften up' the defences. The nearest land masses capable of supporting such an effort were those of the Marshall islands group to the north-west of Guadalcanal. Taking the Marshall islands group would provide the bases needed to launch an offensive against the Mariana islands group, but the Marshall islands group was cut off from direct communications with Hawaii by a garrison on the small island of Betio, on the western side of Tarawa atoll in the Gilbert islands, a wide-flung group of atolls at the edge of the Japanese defensive perimeter established by July 1942.

Thus, in order to pave the way for an eventual invasion of the Mariana islands, the battle had to start far to the east at Tarawa. The Japanese were fully conscious of the strategic importance of the Gilbert islands group, and had invested considerable resources in the fortification of Tarawa, with particular emphasis on the defence of Betio, the atoll’s most important constituent island. The garrison comprised primarily 2,600 high-quality troops of the 3^rd Special Base Force (ex-6^th Yokosuka Special Naval Landing Force that had arrived on 17 March) and 7^th Sasebo Special Naval Landing Force, and in order to bolster the defences, 1,000 Japanese and 1,200 Korean workers were also delivered to the island as the personnel of the 111^th Construction Unit and 4^th Fleet Construction Department. Some 14 coast-defence guns, including some 8-in (203-mm) weapons received from their British manufacturer in 1908, were emplaced round the island in concrete bunkers. A total of 500 pillboxes, 'stockades' build from palm logs, and 40 pieces of artillery were also scattered around the island, and an airfield was cut into the bush along the island’s highest portion. Trenches connected all points of the island, allowing troops to move where needed under some sort of cover. Rear Admiral Keiji Shibasaki, commanding the 4,866-man Gilberts Area Defence Force, had boasted that it would take one million men a century to take Tarawa.

Betio is shaped approximately like a long, thin and slightly bent triangle with its point in the east and base in the west. The lagoon of the atoll lies to the north and east of Betio, with the entire north coast of the island in the shallow waters of the atoll’s lagoon, and the southern and western sides in deeper water. An attack would almost certainly have to approach from the lagoon as the deeper water in the south offered no reasonable landing areas. In order to prevent this, the Japanese had constructed a large wall across the lagoon just behind the high water mark. Behind this a series of machine gun posts and pillboxes was constructed to engage anyone trying to get over the wall. A long northward-angled pier was built from the western end of the island, allowing cargo ships to be unloaded out past the reef and shallow waters, while still allowing them to anchor in the protected waters of the lagoon.

The US resources for 'Galvanic' were first concentrated at Pearl Harbor and elsewhere in the Hawaiian islands group before being despatched to forward bases in places such as the Fiji and New Hebrides island groups for final training. The US invasion force was the largest yet put together for a single operation, and comprised 17 aircraft carriers, 12 battleships, eight heavy and four light cruisers, 66 destroyers and 36 transport vessels, as well as the ground force of some 35,000 men of Major General Julian C. Smith’s 2^nd Marine Division (2^nd, 6^th and 8^th Marines as well as the 10^th Marine Artillery) and part of Major General Ralph C. Smith’s 27^th Division of the US Army.

The organisation for massive offensive moves over considerable distances, including 'Galvanic', was readied in the form of Vice Admiral Raymond A. Spruance’s new 5^th Fleet (seven battleships, eight aircraft carriers under the command of Rear Admiral Charles A. Pownall, seven heavy and three light cruisers, and some 34 destroyers), Rear Admiral Richmond K. Turner’s 5^th Amphibious Force, Major General Holland M. Smith’s V Amphibious Corps (100,000 men), and Rear Admiral John E. Hoover’s land-based air assets of the Defense Forces and Land-Based Air (TF57) comprising, in the Ellice islands group, the growing strength of Major General Willis H. Hale’s 7^th AAF operating as the Striking Group (TG57.2) with 90 Consolidated B-24 Liberator heavy bombers, the Search and Reconnaissance Group (TG57.3) with six naval squadrons, and Brigadier General Lewie G. Merritt’s Ellice Islands Defense and Utility Group (TG57.4) with the 4^th Marine Base Air Defence Wing, three inshore patrol squadrons and one air transport squadron.

Many of the naval and marine assets had previously been Halsey’s 3^rd Fleet for operations in the Solomon islands.

The 'Galvanic' operation was schemed by Turner and Smith as a two-part undertaking, with a Northern Attack Force (TF52 despatched from Pearl Harbor on 10 November) under Turner himself to tackle Makin, and a Southern Attack Force (TF53 despatched from the New Hebrides on 13 November) under Rear Admiral Harry W. Hill to take Tarawa in an operation named 'Longsuit'. The two task forces met on 17 November mid-way between Baker and Canton islands and replenished. Support for the operation was to be provided by TF50, whose TG50.1 and TG50.2 sailed from Pearl Harbor, and TG50.3 and TG50.5 from Espíritu Santo.

In order to soften the defences and isolate the landing area, Pownall’s Carrier Interceptor Group (TG50.1) made carrierborne air attacks on Mili during 19 November using the fleet carriers Yorktown and Lexington, light carrier Cowpens, battleships South Dakota and Washington, and destroyers Nicholas, Taylor, La Valette, Izard, Charrette and Conner; Rear Admiral Arthur W. Radford’s TG50.2 attacked Makin with the fleet carriers Enterprise, light carriers Belleau Wood and Monterey, battleships Massachusetts, North Carolina and Indiana, and destroyers Boyd, Bradford, Brown, Fletcher, Radford and Jenkins; Rear Admiral Alfred E. Montgomery’s TG50.3 attacked Tarawa with the fleet carriers Essex and Bunker Hill, light carrier Independence, cruisers Chester, Pensacola, Salt Lake City and Oakland, and destroyers Erben, Hale, Bullard, Kidd and Chauncey; and Rear Admiral Frederick C. Sherman’s TG50.4 attacked Nauru with the fleet carrier Saratoga, light carrier Princeton, cruisers San Diego and San Juan, and destroyers Stack, Sterett, Wilson and Edwards.

US intelligence had confirmed that Makin was by far the softer of the two objectives, but the command team opted to capture Makin first as any Japanese riposte (by air from the Mariana islands group or by sea from the Combined Fleet's base at Truk in the Caroline islands) would reach Makin first. The force thus allocated to the capture of Makin was Turner’s Northern Attack Force (TF52) in the form of the 6,472 men of the 27^th Division’s 165^th Regimental Combat Team and 105^th Battalion Landing Team landed from the troop transports Leonard Wood, Neville, Pierce and Calvert, the supply transport Alcyone and the dock ship Belle Grove (carrying amtracks and the 193^rd Tank Battalion) of the Transport Group (TG52.1), escorted by the destroyers Mustin, Kimberly, Burns and Dale of the Destroyer Screen.

Fire support was provided by Rear Admiral Charles D. Griffin’s Fire Support Group (TG52.2) with the battleships New Mexico, Pennsylvania, Idaho and Mississippi, heavy cruisers Minneapolis, San Francisco, New Orleans and Baltimore, and destroyers Dewey, Hull, Maury, Gridley, Phelps and MacDonough, and air support by Rear Admiral Henry M. Mullinix’s Air Support Group (TG52.3) with the escort carriers Liscome Bay, Coral Sea and Corregidor, and destroyers Morris, Franks, Hoel and Hughes of the Destroyer Screen, which also included the minesweeper Revenge.

There was also the Makin LST Group (TG54.4) with three tank landing ships each carrying one tank landing craft, screened by the destroyer Dale.

The assault force of inexperienced New York national guardsmen reduced Makin’s 798-man garrison (some 300 troops of the 3^rd Special Base Force's Makin Detachment, 100 aviation personnel and 400 labourers of the 111^th Construction Unit and 4^th Fleet Construction Department, all under Lieutenant Seizo Ishikawa) in four methodical but uncomplicated days between 20 and 23 November. The Americans were largely inexperienced and fought poorly in the tactical sense, losing 218 men (including 64 dead) and capturing only 106 Japanese including just one soldier.

As soon as the island was secure, army engineers attempted to construct an airfield on the western end of Butaritari islet, but this area proved too swampy. A 7,000-ft (2135-m) runway was later constructed on sandy ground: completed in January 1944, this could not support heavy bombers.

On 24 November the submarine Nautilus and destroyer Gansevoort shelled the Japanese positions on Abemama, leading to losses among the defenders, whose survivors committed suicide. By 28 November the remaining islands of the atoll and neighbouring Abemama had been occupied and the construction of an airfield there was started.

The only Japanese external reaction took the form of air and submarine attacks. In the latter, Independence received a torpedo hit on 20 November, the day on which a Japanese submarine group arrived off Makin after an unsuccessful patrol off the Hawaiian islands group. I-75 destroyed Liscome Bay with three torpedoes on 23 November: the ship blew up and sank, taking with her 644 out of a crew of 916 men, and the surviving 272 men were rescued by the destroyers Morris and Hughes. There was much bitterness in the US Navy over the escort carrier’s loss, for the navy felt that had the army secured the island more quickly, the escort carrier would not have been required to linger in the area as a prime target for submarines.

However, the Japanese also suffered losses: I-35 was sunk on 23 November by the destroyers Frazier and Meade off Tarawa, and on the next day Ro-38 was sunk by the destroyer Cotton, also off Tarawa. I-40 was sunk on 25 November by Radford while attempting to attack off Makin, I-39 was sunk on 26 November by Boyd off Makin and I-21, summoned from the South Pacific, was sunk on 29 November by aircraft from the carrier Chenango.

On the day that 'Galvanic' was launched, substantially larger US forces began the more important 'Longsuit' against the stronger defences of Tarawa.

The final objective initially allocated to 'Galvanic' was Nauru island. The war had reached this inland on 6 December 1940, when the German commerce raiders Komet and Orion, disguised as the Norwegian Narvik and Japanese Nanyo Maru, sank five British freighters awaiting loading with phosphate fertiliser. The captured survivors were released by the Germans on Emirau island near the end of the month. An Australian artillery troop was then deployed to the island as a nominal defence force. Mining and transport operations continued until 9 December 1941, when Japanese aircraft from the Marshall islands made a bombing attack. The Chinese and Europeans, other than seven including the administrator, Lieutenant Colonel F. R. Chalmers and some Australian coast watchers, were evacuated in February 1942 by a French destroyer and a steamer.

On 25 August 1942 the Japanese occupied the now undefended island and garrisoned it with two companies of the 43^rd Guard Force from the Caroline islands group. Work on an airfield was soon started on the south-western part of the coast, and this was completed in March 1942. In August 1942 the island was reinforced as a result of the US Marine raid on Makin island, and in February 1943 the occupying unit was designated the 43^rd Guard Force Despatched Landing Force, which was subordinated to the Gilbert Islands Area Defence Force. The Japanese shipped some 1,200 Nauruans to Truk as forced labourers, of whom about one-third died on Truk before the end of the war.

B-24 heavy bombers from Funafuti first bombed Nauru on 20 April 1942. Especially heavy attacks were executed on the eve of 'Galvanic' in November 1943 to neutralise this outlying island. The USA had initially desired to seize Nauru as a base to support operations into the Marshall and Caroline island groups, with the operation scheduled for November 1943 at the same time as the US forces took Tarawa and Abemama atolls in the Gilbert islands. It was assessed that the seizure of Nauru would require one division, which would land on the north-western part of the coast.

The 27^th Division began training for the mission, but then it came to be believed that Nauru was too strongly defended and too difficult to support while operations were being conducted in the Gilbert islands off to the east, and Makin replaced Nauru in US planning. Air attacks by the USAAF and US Navy on the isolated Japanese garrison continued to the end of the war when, on 14 September 1945, Captain Hisayuki Soeda of the Japanese navy surrendered his garrison of 3,700 men to Brigadier J. R. Stevenson of the Australian army.