Invasion of Tulagi (May 1942) - Background

Background

On 7 December 1941, the Japanese attacked the U.S. Pacific fleet at Pearl Harbor, Hawaii. The attack crippled most of the U.S. Pacific Fleet's battleships and started a formal state of war between the two nations. In launching this war, Japanese leaders sought to neutralize the American fleet, seize possessions rich in natural resources, and obtain strategic military bases to defend their far-flung empire. Soon after, other nations—including the United Kingdom, Australia, and New Zealand—joined the U.S. as Allies in the war against Japan. In the words of the Japanese Navy's Combined Fleet "Secret Order Number One", dated 1 November 1941, the goals of the initial Japanese campaigns in the impending war were to, "(eject) British and American strength from the Netherlands Indies and the Philippines, (and) to establish a policy of autonomous self-sufficiency and economic independence." To support these goals, during the first few months of 1942 Japanese forces also attacked and took control of the Philippines, Thailand, Malaya, Singapore, the Netherlands East Indies, Wake Island, New Britain, the Gilbert Islands, and Guam.

Vice Admiral Shigeyoshi Inoue—commander of the Japanese 4th Fleet (also called the "South Seas Force") consisting of most of the naval units in the South Pacific area—advocated the seizing of Lae, Salamaua, and Port Moresby in New Guinea and Tulagi in the Solomon Islands. Inoue believed that the capture and control of these locations would provide greater security for the major Japanese base at Rabaul on New Britain. Japan's Naval General Staff endorsed Inoue's argument and began planning further operations, using these locations as supporting bases, to seize Nauru, Ocean Island, New Caledonia, Fiji, and Samoa and thereby cut the supply lines between Australia and the U.S., with the goal of reducing or eliminating Australia as a threat to Japanese positions in the South Pacific.

The Imperial Japanese Army supported the idea of taking Port Moresby and in April 1942, with the Japanese Navy, developed a plan for the attack that was titled "Operation Mo". The plan also included the seizure of Tulagi, a small island in the southern Solomon Islands, where a seaplane base would be set up for potential air operations against Allied territories and forces in the South Pacific. Although Japanese Admiral Isoroku Yamamoto—commander of the Combined Fleet—was concurrently planning an operation that he hoped would lure the U.S. Pacific Fleet into a decisive showdown in the central Pacific, he detached some of his large warships to support the Mo operation and placed Inoue in charge of the naval portion of the operation.

A large force consisting of two heavy aircraft carriers, one light aircraft carrier, a seaplane carrier, nine cruisers, and 13 destroyers—split into several elements—was to guard the Japanese Port Moresby invasion convoy as well as to engage any Allied naval warships that approached to contest the invasion. The Tulagi invasion force, consisting of the destroyers Kikuzuki and Yūzuki, minelayer/transports Okinoshima, and Kōei Maru, auxiliary minesweepers Wa #1, Wa #2, and transports Hagoromo Maru, Noshiro Maru #2, Tama Maru, and Azumasan Maru, subchasers Toshi Maru #3 and Tama Maru #8 and commanded by Rear Admiral Kiyohide Shima (flag on Okinoshima), departed from Rabaul on 30 April and headed towards the Solomon Islands. Rear Admiral Aritomo Gotō provided air cover for the Tulagi invasion with his Covering Group of one light carrier (Shōhō), four cruisers, and one destroyer located just west of the central Solomons. A separate Cover Force (sometimes referred to as the Tulagi Support Group)—commanded by Rear Admiral Kuninori Marumo and consisting of two light cruisers, the seaplane tender Kamikawa Maru, and three gunboats—joined the Covering Group in supporting the Tulagi invasion. Once Tulagi was secured on 3 or 4 May, the Covering Group and Cover Force were to reposition to help cover the Port Moresby invasion.

At the time, Tulagi was the capital of the British Solomon Islands Protectorate, which included all of the islands of the Solomons except Bougainville and Buka. William Sydney Marchant, the British Resident Commissioner of the Solomons and commander of the local defense forces—described by historian Walter Lord as a "bewildered elderly Englishman"—directed the evacuation of most of the white civilian residents to Australia in February 1942. Marchant was evacuated to Malaita the following month.

The only Allied military forces at Tulagi were 24 commandos from the Australian Army's 2/1st Independent Company, under Captain A. L. Goode, and about 25 personnel from 11 Squadron RAAF, under F/O R. B. Peagam, operating a seaplane base on nearby Gavutu-Tanambogo with four PBY Catalina maritime patrol aircraft. Three Allied coastwatchers were also located nearby, on Guadalcanal island. The task of the coastwatchers was to report on any enemy movements, or suspicious activity, that they observed in the vicinity of their stations. In the belief that it might prevent them being executed for espionage, all of the coastwatchers were commissioned as Royal Australian Naval Volunteer Reserve officers, and they were directed by Lieutenant Commander Eric Feldt, who was located at Townsville in Australia.

Throughout most of April, the Japanese conducted "desultory" bombing raids on Tulagi with aircraft based at Rabaul or nearby that caused little, if any, damage. The coastwatchers on Guadalcanal were usually able to radio advance warning to the Australian troops on Tulagi of the approaching Japanese aircraft, but the troops did not have large enough weaponry—three Vickers machine guns and one Bren light machine gun—to seriously challenge the Japanese bombers. On 25 April, Tulagi was bombed by eight Japanese aircraft. Similar raids occurred daily over the next week, with one raid on 1 May heavily damaging one of the Catalinas at Gavutu. The remaining Catalinas successfully evacuated that same day.

Allied intelligence personnel had deciphered much of the Japanese Mo plans through radio intercepts at the Allied Fleet Radio Units (radio intelligence centers) in Melbourne, Australia and Pearl Harbor, Hawaii. Based on this intelligence, on 22 April, U.S. Admiral Chester Nimitz—stationed at Pearl Harbor—directed Allied forces towards the Coral Sea area to interdict the Japanese Mo operation. On 27 April, the U.S. aircraft carrier USS Yorktown's Task Force 17 (TF 17), under the command of Vice Admiral Frank Jack Fletcher, sortied from Tonga and was joined by the U.S. carrier USS Lexington's TF 11 300 nmi (350 mi; 560 km) northwest of New Caledonia on 1 May. That same day, Fletcher detached TF 11 to refuel, expecting to rejoin with Lexington and her escorts on 4 May at a predetermined location in the Coral Sea.