a deptherapy blog

29 Aug2018


by Dr. Richard Cullen | 29th August 2018

Funded by the Chancellor of the Exchequer’s 2016 Libor Fund

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Chuuk Lagoon (Truk) is a part of the Federated States of Micronesia. The Federated States have a seat at the United Nations.

The Federated States of Micronesia abbreviated FSM and also known as Micronesia) is an independent sovereign island nation and a United States associated state consisting of four states – from west to east, Yap, Chuuk, Pohnpei and Kosrae. In 1979 the four islands ratified a new constitution to become the FSM.

They are spread across the Western Pacific Ocean. Together, the states comprise around 607 islands (a combined land area of approximately 271 square miles that cover a longitudinal distance of almost 1,678 miles, just north of the equator. They lie northeast of New Guinea, south of Guam and the Marianas, west of Nauru and the Marshall Islands, east of Palau and the Philippines, about 1,802 miles north of eastern Australia and some 4,000 km (2,485 mi) southwest of the main islands of Hawaii.

While the FSM's total land area is quite small, it occupies more than 1,000,000 square miles of the Pacific Ocean, giving the country the 14th largest Exclusive Economic Zone in the world. The capital is Palikir, located on Pohnpei Island, while the largest city is Weno, located in the Chuuk Atoll.

Each of its four states is centred on one or more main high islands, and all but Kosrae include numerous outlying atolls. The Federated States of Micronesia is spread across part of the Caroline Islands in the wider region of Micronesia, which consists of thousands of small islands divided among several countries. The term Micronesia may refer to the Federated States or to the region as a whole.

The FSM was formerly a part of the Trust Territory of the Pacific Islands (TTPI), a United Nations Trust Territory under U.S. administration, but it formed its own constitutional government on May 10, 1979, becoming a sovereign state after independence was attained on November 3, 1986 under a Compact of Free Association with the United States. Other neighbouring island entities, and also former members of the TTPI, formulated their own constitutional governments and became the Republic of the Marshall Islands (RMI) and the Republic of Palau (ROP).


Chuuk Islands. Chuuk Islands, formerly Truk Islands or Hogoleu Islands, cluster of 17 much-eroded high volcanic islands in the Federated States of Micronesia, western Pacific Ocean. The name Chuuk means “high mountains” in the Chuukese language, one of several Malayo-Polynesian languages that are used in the islands.

Chuuk is a complex atoll composed of a circle of reefs and about forty low coral islets enclosing a lagoon of 48 to 64 kilometres in diameter and, within it, seventeen high Islands of volcanic origin, with a total land area of 86 square kilometres. There are two major seasons, a dry one with northeast trade winds from November to June and a wet one with light winds from the south and southwest.


As I said in an earlier BLOG you can’t help, as you look at the islands of the atoll, but to think of the opening scenes of the movie Jurassic Park as the helicopter flies towards it and the theme tune plays


The ancestors of the Micronesians settled over four thousand years ago. A decentralized chieftain-based system eventually evolved into a more centralized economic and religious culture centered on Yap Island.

Nan Madol, consisting of a series of small artificial islands linked by a network of canals, is often called the Venice of the Pacific. It is located on the eastern periphery of the island of Pohnpei and used to be the ceremonial and political seat of the Saudeleur dynasty that united Pohnpei's estimated 25,000 people from about AD 500 until 1500, when the centralized system collapsed.


First the Portuguese in search of the Spice Islands (Indonesia) and then the Spanish—reached the Carolines in the sixteenth century. The Spanish incorporated the archipelago to the Spanish East Indies through the capital, Manila, and in the 19th century established a number of outposts and missions. In 1887, they founded the town of Santiago de la Ascension in what today is Kolonia on the island of Pohnpei.

Following defeat in the Spanish–American War, the Spanish sold the archipelago to Germany in 1899 under the German–Spanish Treaty of 1899. Germany incorporated it into German New Guinea.

During World War I, it was captured by Japan. Following the war, the League of Nations awarded a mandate for Japan to administer the islands as part of the South Pacific Mandate.


Chuuk Lagoon’s recorded history begins with early Spanish domination, followed by German acquisition after the Spanish-American war about 1896, and then a Japanese Mandate from the League of Nations upon Germany’s defeat in 1918.


The Japanese era saw a great build-up of arms and bases in advance of a wide military blitz over the Western Pacific. The blitz was supplied heavily from facilities at Truk, where often more than 1,000 merchant and war ships moored in readiness for further deployment.

Five airfields supporting close to 500 aircraft were constructed to provide a protective shield over Truk’s Gibraltar-like facilities. A deep lagoon, high islands and circling barrier reef added extensive natural protection. One such airfiels was based on Eten Island that was described as an unsinkable aircraft carrier but now is overgrown and we visited it between dives and enjoyed fresh coconut milk and coconut fleas.

Patrol boats, torpedo boats, submarines, tugs, landing craft, gunboats and mine sweepers contributed to the final defences and service needs to maintain this big base.

Chuuk Lagoon was considered the most formidable of all Japanese strongholds in the Pacific. This reputation caused an overconfident Chuuk command to relax their vigil against invasion, in spite of U.S. forces fast approaching from the East. Supplies from Japan had almost ceased, due to immense success of U.S. submarines finally equipped with torpedoes finding their mark. Supply convoys receiving nearly 90% losses en-route to Truk, deprived the garrison of needed food, fuel and new armaments desperately required to maintain its supportive strength.


Operation Hailstone 17–18 February 1944, was a massive United States Navy air and surface attack on Chuuk Lagoon conducted as part of the American offensive drive against the Imperial Japanese Navy (IJN) through the Central Pacific Ocean during World War II.

Prior to Operation Hailstone, the IJN had used Chuuk as an anchorage for its large Combined Fleet. The coral atoll surrounding Chuuk’s islands created a safe harbour where the few points of ingress and egress had been fortified by the Japanese with shore batteries, antiaircraft guns, and airfields.

American estimates of Chuuk's defences and its role as a stronghold of the Japanese Navy led newspapers and military men to call it the "Gibraltar of the Pacific", or to compare it with Pearl Harbour. Chuuk's location in the Caroline Islands also made it an excellent shipping hub for armaments and aircraft moving from Japan's home islands down through the South Pacific Mandate and into the Japanese "Southern Resources Area".

By early 1944, Truk was increasingly unsustainable as a forward base of operations for the Japanese. To the west, American and Australian forces under General Douglas MacArthur had moved up through the Southwest Pacific, isolating or overrunning many Japanese strong points as part of Operation Cartwheel. The U.S. Navy, Marine Corps, and Army under the command of Admiral Chester W. Nimitz, had overrun the most important islands in the nearby Gilbert Islands and Marshall Islands, and then build numerous air bases there.

As a result, the Japanese Navy had to relocate the Combined Fleet's forward base to the Palau Islands, and eventually to Indonesia, and the Fleet had begun clearing its major warships out of Chuuk before the Hailstone attack struck.

An overflight by two US surveillance planes prior to the operation led to the planes being observed by the Japanese and as a result the Battleship Yamato and all other capital ships were moved out of the Lagoon.

The three carrier task groups committed to Hailstone moved into position and began launching their first fighter sweep 90 minutes before daybreak on 17 February 1944. No Japanese air patrol was active at the time as the IJN's 22nd and 26th Air Flotillas were enjoying shore leave after weeks on high alert following the Liberator sightings. Similarly problematic for the Japanese, radar on Truk was not capable of detecting low-flying planes — a weakness probably known and exploited by Allied intelligence organizations. Because of these factors, U.S. carrier aircraft achieved total surprise.

Japanese pilots scrambled into their cockpits just minutes before TF 58 planes arrived over Eten, Param, Moen and Dublon islands. Though there were more than 300 Imperial Japanese Navy Air Service (IJNAS) and Imperial Japanese Army Air Service (IJAAS) planes present at Truk on the first day of attacks, only about half of them were operational compared with over 500 operational aircraft among the carriers of TF 58. U.S. Navy fighter pilots in their Grumman F6F Hellcats, with the advantages of speed, altitude and surprise, achieved a one–sided victory against IJNAF pilots flying the inferior Mitsubishi A6M Zero. As many as 30 of the 80 Zeros sent up in response to the fighter sweep were shot down, compared with four Hellcats reported lost. Only token aerial resistance was encountered for the rest of the morning; almost no Japanese aircraft were present by the afternoon.

Due to the lack of air cover or warning, many merchant ships were caught at anchor with only the islands' anti-aircraft guns for defence against the U.S. carrier planes. Some vessels outside the lagoon already steaming towards Japan were attacked by U.S. submarines and sunk before they could make their escape. Still others, attempting to flee via the atoll's North Pass, were bottled up by aerial attack and by Admiral Spruance's surface force, Task Group 50.9, which circumnavigated Truk bombarding shore positions and engaging enemy ships.

Torpedo bomber and dive bomber squadrons from the carrier air groups (CAGs) were responsible for the bulk of the damage inflicted on Japanese ground facilities. Early on the first day of Hailstone, Grumman TBF Avenger torpedo bomber squadrons from USS Enterprise's Air Group 10 (CAG-10) and USS Intrepid's CAG-6 dropped fragmentation and incendiary bombs on runways at Eten Island as well as the seaplane base on Moen Island. Dozens of aircraft were damaged or destroyed, further blunting any possible response by the Japanese to the strikes. Subsequent joint attacks by dive bombers and Avenger torpedo bombers cratered runways and destroyed hangar facilities.

Morning strikes were also launched against shipping targets in the lagoon. Lieutenant Commander (later Rear Admiral) James D. Ramage, commanding officer of Dive Bombing Squadron 10 (VB-10), is credited with sinking the previously damaged merchant tanker Hoyo Maru.[13] Lieutenant James E. Bridges and his crew in one of Intrepid's Torpedo Squadron 6 (VT-6) Avengers scored a direct hit on the ammunition ship Aikoku Maru. The bomb blast set off a tremendous explosion, which immediately sank the ship and apparently engulfed the plane as well, killing all three men inside.

The Hailstone attack on Chuuk caught a good number of Japanese auxiliary ships and cargo ships in the harbour, as well as some warships. Between the air attacks and surface ship attacks over the two days of Operation Hailstone, the worst blow against the Japanese was about 250 warplanes destroyed. Also, about forty ships — two light cruisers, four destroyers, nine auxiliary ships, and about two dozen cargo vessels — were sunk.

Considerable damage was inflicted on the various island bases, including dockyards, communications centres, supply dumps, and its submarine base. Chuuk remained effectively isolated for the remainder of the war, cut off and surrounded by the

American island hopping campaign in the Central Pacific, which also bypassed important Japanese garrisons and airfields in the Bismarck Archipelago, the Caroline Islands, the Marshalls, and the Palaus. Meanwhile, the Americans built new bases from scratch at places like the Admiralty Islands, Majuro, and Ulithi Atoll, and took over the major port at Guam.

After a follow up attack in April, 1944, Truk was reduced to rubble with over 70 shipwrecks, 400 aircraft destroyed or sunk, and the menace of this big fortress completely eliminated. The U.S. forces declined direct engagement with the 40,000 troops at Truk, and after these attacks, starvation consumed many of the defenders and native people before a complete Japanese surrender late in 1945.