| Conventional Long Name: | Naval Base Ulithi Caroline Islands |
| Common Name: | US Naval Base |
| Established Event1: | US Navy Base |
| Established Date1: | 1944 |
| Utc Offset: | +10 and +11 |
9.97°N 139.67°WNaval Base Ulithi was a major United States Navy base at the Ulithi Atoll in the Caroline Islands in the western Pacific Ocean, to the north of New Guinea during World War II. The base was built to support the island-hopping Pacific War efforts of the Allied nations fighting the Empire of Japan. In terms of the number of ships at one base, Naval Base Ulithi was the largest naval base in the world in 1944 and 1945, with over 600 ships at times.[1] [2]
The Caroline Islands are now the Federated States of Micronesia nation. Micronesia comprises the Kosrae State, Pohnpei State, Chuuk State (formerly Truk) and Yap State. After the Spanish–American War in 1898, the islands became a German colony and German naval base. At the start of World War I in 1914 British warships destroyed the German colonial plantation owner's radio station. On 7 October 1914 Japan invaded and took over Yap Island without a battle. Japan and Britain made a treaty giving Japan the Pacific islands north of the Equator, signed at the Treaty of Versailles in 1919. In the 1930s Japan built naval and airbases on many of the islands. Truk Lagoon was the largest and strongest of these bases. The United States Army Air Forces bombed the Truk base, but it was bypassed in the amphibious landing war. Japan's Truk base had five airfields, fleet anchorage, a few seaplane bases, torpedo boat bases, repair facilities, and later a radar station. Japan also built a large base at Ponape, now Pohnpei. By February 1944 US bombers had destroyed Truk, and by sea, the US Navy had cut off Truk and its 5,000 Japanese troops. The US also bypassed Ponape in the Senyavin Islands and its 8,000 troops.[3]
The US Army 81st Division landed unopposed on Ulithi on 23 September 1944. Soon US Navy Seabees started work building the large base at Ulithi. The survey ship found the lagoon was well protected and usable for fleet anchorage, with depths ranging from 80 to 100 feet. The Ulithi coral reef is about 20 miles long and 10 miles wide with over 30 small islands; the largest island is only half a square mile in area. The four largest islands are Sorlen, Falalop, Asor, and Mogmog, and bases were built on all four. Japan bombed the US base at Ulithi a few times, with only marginal damage.[4]
Naval Base Ulithi was in use from 1944 to 1945, as part of US Naval Base Carolines,for staging operations and attacks on Japanese bases to the north. The US Navy Seabee 18th Special Battalion arrived on 1 October, followed by the 88th Naval Construction Battalion on 11 November. The Seabees did major construction on five islands of the atoll. The main projects were building a large fleet recreation center on Mogmog Island for 20,000 troops, docking piers, small plane airstrips, seaplane base, pontoon piers and camps. On Mogmog Island the Seabees built the Seabee base camp and Seabee supply depot.[5] On Sorlen Island a 1,600-place theatre, a large landing craft camp, 1,600-man mess hall, Naval headquarters, Marine aviation camp and 100-bed Naval hospital were constructed. Over 9,000 men were stationed at the base to run the operations.[6] [7] The Seabee 58th Naval Construction Battalion did R&R at Ulithi before departing to Okinawa Island.[8] After Typhoon Cobra in December 1944, Naval Base Ulithi sent out ships to pick up survivors of ships that had sunk in the storm. Some ships that were damaged in the storm were repaired at Ulithi.[9] [10]
Ulithi had a large fleet anchorage used for staging and repair of ships. The Seabees built an airbase to support half of a night fighter squadron, a utility squadron, and a light inshore patrol squadron. At the airbase, the Navy kept up to 150 aircraft fighter planes to replace any lost on aircraft carriers. Staging facilities for transport aircraft were constructed. A large camp was built for the maintenance crews of planes and ships. A camp was built to house crews of ships under repair. A supply depot was built to support the ships, planes, and troops at Ulithi. Most supplies like fuel, ammunition, and spare parts were stored in cargo ships in the atoll and unloaded as needed. Seabees handled over 20,000 tons of cargo per month.
The 18th Special departed 25 May 1945 to Leyte-Samar Naval Base. On 10 October 1944, part of the 6th Special Battalion arrived at Ulithi for unloading and loading of ships, the 6th handled over 12,000 tons of cargo per month. The 6th departed in June 1945, ending its work. The 51st Battalion arrived on 8 October 1944 and widened, lengthened, and improved Falalop Airfield. A 3,500-by-150-foot fighter runway was built. The 51st also built a fuel tank frame and fuel pier.[11] On 16 April 1945, the Seabee Naval Construction Battalion Detachment 1044 arrived. Most of the 1044th worked on damage control and repair sections at the base. The 1044 departed 25 July 1945, ending their work.[12]
The 88th Naval Construction Battalion departed Ulithi on 7 February 1945 and arrived at Bobon, Samar, Philippine Islands on 10 February. There they built a PT boat repair base as part of the Leyte-Samar Naval Base. On 8 November 1944, Naval Construction Maintenance Unit 603 arrived to do general maintenance of the airstrip. The Fleet Post Office at Ulithi was #3011. When Leyte-Samar Naval Base was completed much of the operation at Ulithi was transferred to it, departing on 7 May 1945. During its operation the base supported the nearby Naval Base Kossol Roads.[13] [14] [15]
See main article: United States Fifth Fleet, United States Third Fleet and William Halsey Jr.. The United States Fifth Fleet used Ulithi for staging, including: Philippines campaign, Operation Hailstone and the troop landings at Okinawa. In March 1945 106 destroyers, 29 aircraft carriers, 15 battleships, and 23 cruisers departed for Okinawa. The base was kept secret until found by Japan,[16] [17] and Japan attacked the Fifth Fleet at Ulithi in Operation Tan No. 2 on 11 March 1945 using long-range kamikaze.[18] [19]
In October 1944 a carrier battle group from Task Force 38 of the United States Third Fleet under William Halsey arrived at Ulithi for resupply. Murderers' Row was the nickname given to the Third Fleet's aircraft carriers at anchor in a row at Ulithi. In the row were,,,, and .[20]
After the Third Fleet was hit by Typhoon Cobra in December 1944, it ported in Ulithi. A court of inquiry was held aboard the destroyer tender on 26 December to determine if Halsey should be sanctioned for sailing into the typhoon. The court found "errors in judgment committed under stress of war operations and stemming from a commendable desire to meet military requirements". The typhoon became known as Halsey's Typhoon, as ships were damaged, three destroyers sank and 146 aircraft were lost. The destroyers lost were the,, and ; 790 crewmen died.[21] [22]
The fleet oiler was sunk on 20 November 1944 at Ulithi after being hit by a Japanese kaiten-manned torpedo. The ship exploded and sank with a loss of 63 crew members. Four other kaiten did not hit any other ships. Over 100,000 barrels of fuel oil were stored at Ulithi in tanker ships and land depots. Naval Base Ulithi supported a number of other smaller bases in the Naval Base Carolines.[23]
On 11 March 1945, kamikaze aircraft hit on her stern starboard side in a nighttime raid on Ulithi. Randolph lost 27 men and 105 were wounded. The raid was called Operation Tan No. 2 that took off from Kanoya Air Field. Randolph was quickly repaired at Ulithi and put back in service.[24] [25]
Japan planned another major attack on Ulithi, but it was canceled with the surrender of Japan in September 1945, while the submarines were en route. With the news of surrender, the I-400 fleet returned to Japan.[26] [27]
The United States Coast Guard built a LORAN (Long Range Navigational Signal) station at Ulithi in December 1944 and operated the station on Potoangroas Island till February 1945. For the Korean War the LORAN station was moved to Falalop Island near the Falalop Airfield, as Potoangroas Island was only resupplied by sea, and in rough weather there was no resupply.[33] The Ulithi LORAN Station was closed in February 1962 and moved to Yap Island. In 1978 the Global Positioning System replaced the need for LORAN.[34] [35]
US Navy Seabees turned the swamps and forest on Mogmog Island (Mog Mof) into a large Ulithi fleet recreation center. The Seabees built the Ulithi Seabees camp with barracks and depot. At the depot Seabees stored all the supplies and gear needed to build and maintain the base at Ulithi.
The Mogmog Island recreation center had a bandstand, a refreshment center, a 1,200-seat theatre with a 25-by-40-foot stage, a sport center with 4 baseball diamonds and 200-seat chapel. The recreation center could house up to 8,000 men and 1,000 officers daily. Mogmog Island had a large recreation beach resort for those on leave. The Navy had an ice cream barge that could make up to 500 gallons of ice cream for the troops in 8 hours. The barge would also make fresh bread products. The base officer's and chief petty officer's club was built on Mogmog Island.
Mogmog Airfield was constructed for light aircraft for short trips to the other nearby islands. Off the shore of Mogmog Island in the atoll was the Mogmog floating seaplane base, supported by seaplane tenders.[36] [37]
Naval Base Ulithi headquarters and the military cemetery were built on Asor Island. The 6th Special Naval Construction Battalion was in charge of most burial details. The 63 men lost during the attack on the USS Mississinewa AO-59, were given interment at Ulithi cemetery, as were some of those lost on the USS Franklin. After the war the cemetery was closed as the troops were reinterred in new, permanent cemeteries in the states.[38] [39] [40] [41]
On Sorlen Island a second and small fleet recreation center was built. The main part of the recreation center was the 1,600 seat movie theater. A distillation center and 5,000-gallon storage tanks system was built to make freshwater. While the US Marine fighter base was on Falalop Island, a camp for Marine aviation was built on Sorlen Island, with barrack and mess halls. Naval Base Ulithi has many landing craft used to move gear and personal from ship to ship and ship to shore. On Sorlen Island a large landing craft camp was built. The Fifth Fleet and Third Fleet had hundreds of landing craft used in amphibious landings, that also use the camp and depot for maintaining the crafts when needed. A quonset naval hospital was constructed on Sorlen Island with a 100-bed unit. A power plant was built to supply electricity.Seabees built the Sorlen Airfield for small plane use.[42]
Many US Navy submarines were used in the Pacific War. The submarines attacked warships and sank supply ships that were needed by Japan to resupply their many bases in the Pacific. US subs also did reconnaissance patrols, landed guerrilla special forces and search and rescue missions for downed aircrew men.[43] US submarines had long ranges, but needed to be resupplied with fuel, food, torpedoes and deck gun shells. At Naval Base Ulithi the Navy set up a floating submarine base in the atoll. The submarine tenders USS Sperry (AS-12) and USS Sumner (AGS-5) were stationed in the atoll to supply the submarines. While the submarine was being resupplied, and repaired if needed, crews could have a break (R&R) at the Ulithi's fleet recreation center on Mogmog Island. Some of the subs stationed at the base were: USS Albacore (SS-218), USS Skate (SS-305), and USS Flying Fish (SS-229),[44]
The US Navy set up a large ship and boat repair depot at Naval Base Ulithi. The repair depot provided the fleet with support to keep ships and subs tactically available in the Pacific War with the repair and supply depot, rather than ships having to return to continental United States. The Navy had built special auxiliary floating drydocks that were able to repair battle damage to even the largest ships and do regular maintenance in the field saving ships trans-pacific travel time for repair. Supply store ships were also at the base with the parts needed to keep the fleet ready.[45] The most noted ship repaired at the depot was the USS Franklin (CV-13). The USS Franklin on 19 March 1945 was hit by Japanese bombs off Okinawa. Fire and explosions damaged the ship, killing and wounding many. The crew was able to save the badly damaged ship. Under her own power, she made it to Ulithi repair depot for emergency repairs before going to the Brooklyn Navy Yard for a year-long complete rebuild. The USS Houston (CL-81) and USS Reno (CL-96) also had emergency repairs at Ulithi. USS Hancock (CV-19) and USS Ticonderoga (CV-14) were repaired at the base after kamikaze attacks. The USS Bennington (CV-20) was repaired with a badly damaged flight deck from Typhoon Cobra.[46]
The US Navy set up a two large seaplane base at Naval Base Ulithi, Falalop seaplane base and Mogmog seaplane base. Seaplanes did reconnaissance patrols and search, also rescue missions for downed aircrew mem and survivors of sunk ships. The most common seaplanes at the base were Consolidated PBY Catalina and Martin PBM Mariner. The Mogmog seaplane base take off and landing was a spot marked in the atoll off the fleet recreation center on Mogmog Island.[48] The seaplanes were supported by a floating base of seaplane tenders. The second seaplane base was on Falalop Island. On Falalop Island a seaplane ramp was constructed by the Seabees at one end of Falalop airfield. The seaplane ramp extended from the extreme low tide mark to the seaplane parking hardstand. The Falalop seaplane base was completed on 5 December 1944. Seaplane tenders and land base had stores to supply: food, fuel, ammo, spare parts. The seaplane tender also had housing and mess halls for the aircrew while the seaplane was being serviced. Aircrew on leave could go to Ulithi's fleet recreation center on Mogmog Island. Some seaplane tenders were stationed at Ulithi seaplane base for months. Other seaplane tenders came to Naval Base Ulithi to resupply the ship's stores before returning to a US Naval Advance Base. Some came to Ulithi repair depot to be repaired.[49] Some seaplane tenders at Naval Base Ulithi:
To help protect the base and shipping around the base, Naval Base Ulithi had a fleet of submarine chasers. The submarine chasers were supported by a submarine chaser tender ship: the USS Mindanao (ARG-3) was stationed at Ulithi to support the fleet of submarine chasers and some crash boats. crash boats were fast boats use to rescue downed airmen. Some of the submarine chasers served at Ulithi: USS PC-1137, USS PC-598, USS PC-1136, USS PGM-18, and USS PC-1138.[51] [52] [53]
See also: List of destroyers of the Second World War. Hundreds of US Navy destroyers were used in the Pacific war. Destroyers were used to protect capital ships like aircraft carriers, battleships and heavy cruisers. Destroyers were used to screen and protect convoy of ships. Destroyers were used to hunt submarines and protect amphibious landings at beaches. Destroyers had anti-aircraft guns, radar, and forward-launched ASW weapons, dual-purpose guns, depth charges, and torpedoes.[54] [55] Like the submarines, they needed to be restocked with food, fuel, supplies, and weapons to be kept operational. Ulithi had a large destroyer base, with destroyer tenders. Destroyer tenders could do minor repair work on the ships also, and major work could be done at the Ulithi repair depot.[56] [57]
Destroyer tenders stationed at Ulithi:
For four months (March to June) in 1945 Naval Base Ulithi was used as a major forward Naval hospital. US Navy Hospital ships were stationed Naval Base Ulithi during parts of the war and some were stationed shortly as they joined staging for upcoming invasions. Hospital ships also were able to resupply and refuel at the base.[58]
To protect the many ships at Ulithi the Navy had 1,260 yards of anti-torpedo net installed in the Towachi Channel and 6,390 yards at other inlets to the atoll. The ship USS Tuscana (AKN-3) supplied the nets.[60]
On 13 March 1945, there were 647 ships at anchor at Ulithi, some stationed, some in for repair or resupply. Just before the departure of the fleet to Okinawa there were 722 ships at Ulithi. United States Merchant Navy ships also were unloaded at Naval Base Ulithi to keep the fleet and base supplied.