The battle of Kwajalein (1-4 February 1944) saw the Americans capture the largest island in Kwajalein Atoll in the Marshall Islands after only four days of land fighting (Operation Flintlock)
Kwajalein was to be invaded by the Southern Attack Force (Task Force 52), under Admiral Turner and the Southern Landing Force (Task Group 56.1), made up of the 7th Infantry Division (Major General Charles H. Corlett). Admiral Turner commanded the invasion from the command ships USS Rocky Mount.
Admiral Turner's attack force consisted of four old battleships, 3 heavy cruisers, 21 destroyers, 2 high speed transports (APDs), 3 escort carriers, 12 LCIs and 4 mine sweepers.
Kwajelain island is the largest island in Kwajalein Atoll. It is shaped like a crescent, and is about two and a half miles long and 800 yards wide for most of its length and narrowing to 300 yards wide towards its northern tip. Part of the American plan involved capturing smaller nearby islands to use as artillery bases. The choice was between Carlson (Enubuj) Island to the west or Burton (Ebeye) Island to the north. Burton appeared to be defended, Carlson either un- or lightly defended.
Kwajalein was the HQ of the Japanese 6th Base Force, the unit charged with defending the Marshalls, and in many ways was a rear area. The Japanese expected the Americans to attack somewhere in the eastern Marshalls, and the move right into the heart of the island ground caught them out.
Kwajalein was the second most heavily defended island in the atoll. There were four 12.7cm dual purpose guns in twin mounts, with a battery of two at each end of the island. Both positions were supported by two 150cm searchlights and a mix of 13mm and 7.7mm machine guns. One twin-mounted 13mm machine gun was at the northern end of the island. There were six 8cm dual purpose guns in two three gun batteries on the ocean shore, one 8cm gun on the lagoon shore and one 8cm gun in the blockhouse on the main pier, facing into the lagoon at the northern end of the island. There were forty or so reinforced concrete pillboxes along the ocean shore and at the two ends of the island. There was a large tank ditch east of the airfield.
The Japanese had around 5,000 men in the southern part of Kwajalein Atoll when the Americans invaded. This included 933 men from the Army's 1st Amphibious Brigade, although most of this force had only just arrived and was due to move on fairly soon. Most of the rest of the force was made up of back area staff, construction staff and other less effective troops, and of the 5,000 men only around 1,820 were fully effective combat troops.
The invasion would take place on D+1. The 184th Regimental Combat Team would land on the left and the 32nd Regimental Combat Team on the right.
On 29 January TG 58.3 (Cowpens, Monterey and Bunker Hill) attacked Kwajalein Island itself then moved north-west ready to attack Eniwetok on the following day. On 30 January TG 58.1 took over at Kwajalein.
On 31 January the outlying islands of Carlson, Carlos, Carter and Cecil was all captured without any serious resistance. An artillery base was set up on Carlson, and by late in the afternoon a constant harassing bombardment of Kwajalein had begun. The island was also subjected to a naval bombardment from the San Francisco, Idaho and New Mexico and their screen of destroyers. At 0618 on 1 February the Mississippiand Pennsylvania took over that role. At 0712 the Mississippi closed to within 1,500 yards to begin a broadside bombardment of all visible targets. At around 0745 she switched her attention to Burton, and the Pennsylvania, New Mexico, Minneapolis, New Orleans, San Francisco and eight destroyers began a heavy bombardment of the landing areas at the western end of the island. At the same time the destroyers Ringgold and Sigsbee moved into the lagoon to stop any movement between the islands. On 1 February the Navy fired 7,000 14in, 8in and 5in shells at Kwajalein, in the heaviest pre-invasion naval bombardment of war so far. Another 29,000 rounds were fired by the artillery on Carlson. The various bombardments destroyed most of the fixed fortifications and all of the gun positions on the island.
The invasion itself was conducted over a 500 yard long beach at the western end of the island, named Red Beach 1 on the left (north) and Red Beach 2 on the right (south). The 32nd Regimental Combat Team (Col. Marc. J. Logie) was given the task of landing on the right, where the strongest defences faced the ocean. The 184th Regimental Combat Team (Col Curtis D. O'Sullivan) landed on the left. Each RCT was to land in columns of battalions, with the 1st Battalion, 32nd and 3rd Battalion, 184th, leading the way, with just over 3,000 men between them. They would also be supported by two companies from the 767th Tank Battalion.
The landing craft set off for the beach at 0900. At about the same time carrier aircraft attacked the landing zones once again, before at 0905 the last naval and artillery bombardment began. At 0928 the big guns shifted their fire inland. The attack was opposed by some light Japanese fire, before the first wave hit the beach at 0930, exactly as planned.
On the right the 32nd found itself facing fire from a few surviving pill boxes. The troops had to wait briefly on the beach while the LVTs fired over the sea wall, and one surviving pillbox on the beach was destroyed, before moving inland. On the left the LVTs were able to get a better field of fire inland and the advance began more quickly. By 1122 both of the leading battalions had advanced 150 yards inland without running into much resistance. The biggest problems was caused by the plan to have the first waves of LVTs move to the flanks then go back to pick up more troops - in the event they were unable to move across the beaches had had to move straight back out to sea, causing delays amongst later waves. Other than this, the American build up went smoothly. Tanks, mortars and artillery soon landed on the island, and by the end of the day the Americans had established a firm beachhead at the western end of Kwajalein. They had even reached the western end of the airfield, despite the odd moment of firm resistance. At the end of the first day the front line ran from the coast to the airfield on both sides, then looped around the western end of the airfield. A quarter of the island had already been conquered and six battalions were already ashore.
On many occasions the first night after an amphibious landing saw the Japanese launch fierce counterattacks. On Kwajalein the defenders had been so badly shaken by the events of the day that the attacks were on a smaller scale, but several were launched. The surviving Japanese troops on both sides of the line also made a series of smaller scale attacks that gave everyone a restless night, while the guns at the north-eastern tip of the island were still in action.
On day two (2 February) General Corlett planned to reach the far end of the island. The 32nd Regiment, on the right, was to sweep around the longer side of the island to reach the northern tip, while the 184th Regiment, on the left, was to deal with the defences on the lagoon side. The airfield was soon captured and the deep tank ditch to its east was crossed during the afternoon. The advance bogged down after that. Even so, Japanese resistance was clearly close to its end. The night of 2-3 February passed quietly, without even the expected banzai attack.
On day three (3 February) the Americans fought their way around the bend in the island and began to advance north, into the area with the most buildings, and a number of strong point on the ocean side of the island. The 32nd Regiment, on the right, made the quickest progress, and soon ended up well ahead of the 184th. The Japanese were unable to take advantage of this temporary vulnerability, but they were able to hold up the 184th, as it attempted to advance through a rubble field. It took most of the day, and the commitment of reinforcements, to get the 184th moving again, but by the end of the day the two regiments were side-by-side and only the northern part of the island remained to be conquered.
By the start of day 4 (4 February) on the northern 100 yards of the island remained in Japanese hands. This area contained the ruins of a large number of buildings and several defensive strong points, but most of these were facing out to sea. Although the fighting lasted well into the afternoon, the end was clearly close. There were even a surprisingly large number of prisoners taken, as resistance crumbled. By 1610 General Corlett was willing to announce that all organised resistance had ended, although fighting at the northern end of the island went on to dusk, and that area wasn't secured until 1820.
During the fighting on Kwajalein the Americans lost 177 dead and 1,000 wounded. The Japanese lost around 3,800 dead. The massive naval and air bombardment before the invasion, and the improved planning for an amphibious landing helped reduce American casualties, but their biggest advantage was that the Japanese simply hadn’t expected a landing on Kwajalein.
At the same time as Kwajalein was being cleared, the Americans also invaded Burton Island (3-4 February 1944), clearing the island in two days. A series of other smaller islands also had to be cleared, but by 8 February Kwajalein Attol was declared secure.