[6] Because of the threat by CAF aircraft, the Imperial Japanese Navy (IJN) was unable to use large, slow transport ships to deliver troops and supplies to the island.

The Japanese warships, mainly light cruisers and destroyers from the Eighth Fleet under the command of Vice Admiral Gunichi Mikawa, were usually able to make the round trip down "The Slot" to Guadalcanal and back in a single night, thereby minimizing their exposure to CAF air attack.

These high speed warship runs to Guadalcanal occurred throughout the campaign and were later called the "Tokyo Express" by Allied forces and "Rat Transportation" by the Japanese.

[8] After the third failure, an attempt by the IJN to deliver the rest of the IJA 38th Infantry Division and its heavy equipment failed during the Naval Battle of Guadalcanal from 12 to 15 November.

Therefore, Combined Fleet naval staff officers began to prepare plans for abandoning Guadalcanal and shifting priorities and resources to operations around New Guinea.

The few supplies delivered to the island were not enough to sustain Japanese troops who, by 7 December, were losing about 50 men each day to malnutrition, disease, and Allied ground or air attacks.

The Japanese had delivered almost 30,000 army troops to Guadalcanal since the campaign began, but by December only about 20,000 of that number were still alive; of those, only around 12,000 remained more or less fit for combat duty, with the rest incapacitated by battle wounds, disease, or malnutrition.

Combined Fleet leaders began telling their army counterparts the losses and damage to warships engaged in the resupply effort threatened future strategic plans for protecting the Japanese Empire.

[12] Throughout November, Japan's top military leaders at the IGH in Tokyo continued to openly support further efforts to retake Guadalcanal from Allied forces.

On 11 December two staff officers, IJN Commander Yuji Yamamoto and IJA Major Takahiko Hayashi, returned to Tokyo from Rabaul and confirmed Hattori's, Tsuji's, and Sejima's reports.

Hitoshi Imamura, commander of the 8th Area Army in charge of IJA operations in New Guinea and the Solomons, did not directly recommend a withdrawal from Guadalcanal but openly and clearly described the current difficulties involved with any further attempts to retake the island.

The IGH's top leaders agreed with Sanada's recommendation on 26 December and ordered their staffs to begin drafting plans for the withdrawal from Guadalcanal and establishment of a new defense line in the central Solomons.

By 9 January, the Combined Fleet and 8th Area Army staffs together completed the plan, officially called Operation Ke after a mora in Japanese Kana vocabulary, to execute the evacuation.

At the same time, Japanese air and naval forces would conduct conspicuous maneuvers and minor attacks around New Guinea and the Marshall Islands along with deceptive radio traffic to try to confuse the Allies as to their intentions.

[18] Yamamoto detailed aircraft carriers Jun'yō and Zuihō, battleships Kongō and Haruna – with four heavy cruisers and a destroyer as the screening force – under Nobutake Kondō to provide distant cover for Ke around Ontong Java in the northern Solomons.

An additional 60 floatplanes from the IJN's "R" Area Air Force, based at Rabaul, Bougainville and the Shortland Islands, brought the total number of Japanese aircraft involved in the operation to 436.

Allied analysts determined that the increased radio traffic in the Marshalls was a deception meant to divert attention from an operation about to take place in either New Guinea or the Solomons.

The plan directed the 38th Division, which was currently defending against an American offensive on ridges and hills in the interior of the island, to disengage and withdraw towards Cape Esperance on the western end of Guadalcanal beginning on the 20th.

"[29] On 26 January, a combined US Army and Marine unit called the Composite Army-Marine (CAM) Division advancing westward encountered the Yano Battalion at the Marmura River.

On 1 February, with help from a shore bombardment by the destroyers USS Wilson and Anderson, the Americans successfully crossed the river but did not immediately press the advance westward.

[32] A second large raid was conducted on 27 January by nine Kawasaki Ki-48 "Lily" light bombers escorted by 74 Nakajima Ki-43 "Oscar" fighters from the IJA's 6th Air Division from Rabaul.

[34] Screening the approach of the transport convoy was Task Force 18 (TF 18), under Rear Admiral Robert C. Giffen, with three heavy and three light cruisers, two escort carriers, and eight destroyers.

The "R" Area Air Force's 60 floatplanes were tasked with scouting for the Reinforcement Unit and helping defend against Allied PT boat attacks during the nighttime evacuation runs.

Believing that the force posed a threat to that night's scheduled evacuation run, an airstrike of 13 Aichi D3A2 "Val" dive bombers escorted by 40 Zeros departed Buin, Bougainville to attack the ships.

Beginning at 14:53, destroyer USS De Haven was rapidly hit by three bombs and sank almost immediately 2 mi (1.7 nmi; 3.2 km) south of Savo Island with the loss of 167 of her crew, including her captain.

Meanwhile, Halsey's carrier and battleship task forces remained just beyond Japanese air attack range about 300 mi (260 nmi; 480 km) south of Guadalcanal.

[54] Believing that the Japanese operations on 1 and 4 February had been reinforcement, not evacuation missions, the American forces on Guadalcanal proceeded slowly and cautiously, advancing only about 900 yd (820 m) each day.

[56] Aware of the presence of Halsey's carriers and other large warships near Guadalcanal, the Japanese considered canceling the third evacuation run, but decided to go ahead as planned.

[60] In hindsight, historians have faulted the Americans, especially Patch and Halsey, for not taking advantage of their ground, aerial, and naval superiority to prevent the successful Japanese evacuation of most of their surviving forces from Guadalcanal.

Said Chester Nimitz, commander of Allied forces in the Pacific, of the success of Operation Ke, "Until the last moment it appeared that the Japanese were attempting a major reinforcement effort.