'Cleanslate' was the US seizure of the Russell islands group as the final stage in the campaign to retake the south-eastern end of the Solomon islands group (21 February 1943).

The Russell islands are a small group located about 35 miles (55 km) to the west of Cape Esperance on the north-western tip of Guadalcanal. There are two main islands, Pavuvu to the west and Banika to the east, and a number of islets. The two main islands are separated by Sunlight Channel, which forms an excellent protected deep anchorage. The north-eastern coast of Banika has sufficient flat ground for the construction of airfields. The islands had a number of copra plantations but no other significant facilities before the war. The Japanese used the islands during the Guadalcanal campaign as a staging area for their barge traffic to the south-east, but then abandoned the islands.

Even before the final advance of Major General Alexander McC. Patch’s XIV Corps on Guadalcanal, Allied commanders in the South Pacific Area had been looking at additional measures to counter the Japanese capability for maritime infiltration to the south-east along the chain of the Solomon islands group. The Americans wished to attack New Georgia, but in January 1943 lacked the forces for an undertaking of the required size. However, the occupation of the Russell islands group, lying some 125 miles (200 km) to the south-east of the New Georgia islands group, seemed feasible.

Possession of the Russell islands would deny their use to the Japanese, who had been using the islands as a staging area for their movement of troops to Guadalcanal. The Americans also appreciated that airfields could be built on the Russell islands to shorten the operational air distance from Henderson Field on Guadalcanal to Munda on New Georgia island by about 65 miles (105 km), and that PT-boat and landing craft bases could also be established. Thus Allied possession of the Russell islands would not only strengthen the defence of Guadalcanal but also serve as a useful advanced base and staging area to support the invasion of New Georgia.

On 29 January Admiral William F. Halsey, commanding the South Pacific Area, was authorised by Admiral Chester W. Nimitz, commanding the Pacific Ocean Areas, to proceed with the occupation. Halsey’s first plan was based on infiltration from Guadalcanal by one infantry battalion and anti-aircraft units carried on two destroyer transports. On 30 January, however, Patch reported that there were 400 Japanese in the Russell islands. At that time the Americans were unaware that the Japanese were evacuating their troops from Guadalcanal in 'Ke' (i), and thus could not know how the Japanese would react to the loss of the island.

South Pacific Area intelligence estimates in February assumed that there were between 33,000 and 41,000 Japanese troops in the Solomon islands group on Buka island, Bougainville island, the Shortland islands group, the New Georgia islands group, and at Rekata Bay on Santa Isabel island. The estimates also suggested that the Japanese had 157 aircraft, three cruisers, 21 destroyers and nine submarines in the area, as well as 15 other warships and 30 non-combatant craft in the waters of the Bismarck islands archipelago.

If the Japanese were determined to recapture Guadalcanal, they could be expected to react violently to a US occupation of the Russell islands group, so the US occupation force would therefore have to be strong enough to cope with any Japanese riposte.

It was on 7 February that Halsey ordered the occupation of the Russell islands group, and directed that the landing force should comprise two infantry regimental combat teams, one marine raider battalion, anti-aircraft detachments from a marine defence battalion, and naval base and construction units.

Overall command of the resulting 'Cleanslate' operation was vested in Rear Admiral Richmond K. Turner before, following the end of the amphibious phase and the landing of supplies for 60 days, command of the occupation troops passed to the XIV Corps on Guadalcanal, whose commander would then assume responsibility for the supply of the islands.

Air support for 'Cleanslate' would be provided by the land-based aircraft of Rear Admiral Aubrey W. Fitch’s air element of the South Pacific Force, which were to cover the occupation force’s movement to the Russell islands and the landings, and by executing long-range search and bombardment missions.

South Pacific Area naval forces would also support and cover the invasion. Turner’s 'Cleanslate' Amphibious Force had no large warships, transports or cargo ships: it comprised four destroyers, four destroyer transports, five high-speed minesweepers, 12 tank landing craft, a number of smaller landing craft, a 1,000-ton barge, and the Russell Islands Occupation Force. The transports were to be shielded by eight PT-boats, an integral part of the Amphibious Force, as well as by the South Pacific air and naval forces.

Major General John H. Hester’s Russell Islands Occupation Force comprised Hester’s own 43^rd Division less the 172^nd Regimental Combat Team, which was then at Espíritu Santo.

As the operation was to be launched from Guadalcanal, seven ships moved the 103^rd and 169^th Regimental Combat Teams and supplies for 30 days, five units of fire, and 40% of the 43^rd Division’s vehicles from Nouméa to Koli Point on Guadalcanal. Some 4,000 men of the first echelon landed at Koli Point from three ships between 09.00 and 17.00 on 16 February. The four ships carrying the 4,500 men of the second echelon were unsuccessfully attacked by Japanese bombers about 100 miles (160 km) to the south-east of Guadalcanal on 17 February, and landed the men at Koli Point on the following day. At Koli Point the men of the two regimental combat teams sorted their supplies in preparation for loading the destroyers, minesweepers, destroyer transports, and landing craft.

While the regimental combat teams were moving to Guadalcanal, officers of the 43^rd Division, together with naval and marine officers, reconnoitred the Russell islands group to establish whether of not there were any Japanese troops present, and to select the landing beaches and the sites for airfields and PT-boat bases. They sailed from Guadalcanal on the New Zealand corvette Moa and went ashore in a landing boat at Renard Sound at Banika, the easternmost main island, after dark on 17 February, and the local population assured them that the Japanese had departed. On the next day the patrol examined the area around Paddy Bay at Pavuvu, the largest island, and returned to Guadalcanal on the night of 18/19 February.

The 43^rd Division, which was to use two small echelons in the initial landings, continued its preparations at Koli Point. The first echelon consisted of the divisional headquarters, the 1^st and 2^nd Battalion Teams of the 103^rd Regimental Combat Team, the 43^rd Cavalry Reconnaissance Troop, the 3^rd Marine Raider Battalion, a detachment of the 11^th Marine Defense Battalion, and the 43^rd Signal Company. It assembled on the beach on 19/20 February, and at 05.30 on 20 February loading of the LCT’s began.

By 16.00 the landing craft, destroyers, minesweepers and destroyer transports had been loaded, and the Amphibious Force was ready to depart.

'Cleanslate' was more a shore-to-shore than a ship-to-shore operation. The destroyers, minesweepers, and destroyer transports were loaded with men and matériel, but also towed fully loaded landing craft. Ten of the ships each towed one mechanised landing craft, two personnel landing craft, and one vehicle landing craft; two ships each towed two vehicle landing craft and two personnel landing craft; and one ship towed one vehicle landing craft and one personnel landing craft. A tug towed the barge, and the tank landing craft proceeded under their own power.

The entire movement to the Russell islands group passed without incident. Early in the morning of 21 February, about 10 miles (16 km) to the east of the Russell islands group, the Amphibious Force divided into three units, each of which proceeded to a separate beach to land the troops in accordance with the tactical plan. A preliminary bombardment by the destroyers, minesweepers, and destroyer transports had been prepared, but the absence of the Japanese rendered this unnecessary. By 05.30 all of the landing craft had cast loose their tows and were approaching their assigned beaches, and at 06.00 the assault waves went ashore unopposed.

The plan was executed to schedule and without Japanese interference. The divisional headquarters and and the 1^st Battalion Team of the 103^rd Regimental Combat Team, the 43^rd Signal Company and the 11^th Defense Battalion detachment landed over Yellow beach at Wernham Cove at the southern end of Banika. The 2^nd Battalion Team of the 103^rd Regimental Combat Team and the 43^rd Cavalry Reconnaissance Troop landed over Blue beach on the northern and southern coasts of Renard Sound on Banika. The 3^rd Raider Battalion landed from the destroyer transports over Red beach and Paddy Bay at Pavuvu.

Patrols immediately pushed inland, but found no Japanese. The engineers immediately moved out to locate a source of drinkable water, whose supply was a more pressing problem than the Japanese. By 18.00 all elements of the landing force could communicate by telephone as wire crews had strung a telephone line across Sunlight Channel to connect Banika with Pavuvu. By 19.00 the troops had dug themselves in, and observation posts and outposts had been established.

During this period logistical operations on the beaches were progressing well. The invasion had been effected under radio silence, the Japanese air and naval forces had not interfered, and the unloading had not been interrupted. The commanders had emphasised the necessity for unloading rapidly and moving the supplies inland to keep the beaches clear, so about one-third of the landing force had been assigned to unload the ships and landing craft. Ship unloading details numbered 80 men per reinforced battalion, and 45 men were assigned to each tank landing craft. Besides their naval elements, the beach parties had 200 soldiers or marines per reinforced battalion.

By 10.00 on the following day all craft except the barge had been unloaded and 15 days' supply of B rations, 10 days' supply of C rations, five days' supply of D rations, five units of fire, and 30 days' supply of petrol, oil and lubricants had been landed, and the ships and landing craft then returned to Guadalcanal to embark the second echelon.

The destroyers, minesweepers, destroyer transports and landing craft returned during the morning of 22 February to land the 169^th Regimental Combat Team at Paddy Bay and Yellow beach. Throughout the rest of February tank landing craft transported the remainder of the 43^rd Division (less the 172^nd Regimental Combat Team) from Koli Point to the Russell islands group, and by the end of the month a force of 9,000 men had landed in the islands.

By 16 March 15,669 troops of all services had reached the Russell islands group. Beach and anti-aircraft defences, including long-range and fire-control radar equipments, 155-mm (6.1-in), 90-mm (3.54-in) and 40-mm guns, together with lighter anti-aircraft guns, had been established.

The Japanese launched no naval attack on the Russell islands group by sea, but made frequent air raids on the new US advanced base. The first evidence that the Japanese were aware of the occupation was an air raid on 6 March. As the Russell islands group was still under radio silence, radar warnings had not sent to the islands, but the damage from the raid was slight. Thereafter the Japanese continued to bomb the Russell islands group by day and night, but the radars alerted the troops in time, and fighters from Guadalcanal usually drove the enemy off until the airfields in the Russell islands group had been completed.

By 16 April supplies had reached the prescribed levels (60 days of most types, 10 units of fire for field and sea coast artillery, and 15 units for anti-aircraft artillery), and command of the Russell islands passed from Turner to Patch. Construction of roads, airfields and boat bases had begun in February, and by 15 April the first of the two airfields on Banika was ready for operation. Surfaced with rolled coral, it was then 2,300 yards (2105 m) long and 100 yards (91 m) wide. The PT-boat base at Wernham Cove had gone into operation on 25 February and by 15 February three landing craft bases were operational.

The Allied base in the Russell islands group was then to support further advances to the north-west. Despite the comparative ease of this task, the move served notice on the Japanese that the Americans had not been exhausted by the rigours of the Guadalcanal campaign, and were prepared to harry Lieutenant General Harukichi Hyakutake’s 17^th Army up the length of the chain of the Solomon islands group.

Pavuvu became a staging area for the 43^rd Division for the 'Toenails' assault on New Georgia and for the 1^st Marine Division for the 'Stalemate II' and 'Iceberg' campaigns in the Palau islands group and on Okinawa respectively. The dismantlement of the base began even before the 1^st Marine Division shipped out for Okinawa, and the base was officially closed on 12 June 1946.