- In September 1944, the US Navy captured Ulithi Atoll and used it to support the Allied advance.
- The remote atoll housed hundreds of ships for repair and upgrade and allowed troops to rest.
- Ulithi takes on a new meaning amid rising tensions with China in the western Pacific.
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On September 16, 1944, as US Marines began a full-scale attack on Peleliu, Admiral William Halsey, commander of the US Navy’s 3rd Fleet, ordered the III.
Seven days later, soldiers from the 81st Infantry Division began landing on the coral islands of Ulithi. The Japanese had left the atoll several months earlier and the US landing was not opposed. Within two days, the Americans had completed their first unloading operations.
Roughly between Guam and Palau and about 1,300 miles from Tokyo, Ulithi would have been easy to miss, but within weeks it would become essential to the war effort.
Hundreds of Allied ships would fill its lagoon and thousands of troops would occupy its islands. The remote coral outcrop would allow them to take the fight as far as the shores of Japan.
The largest naval facility in the world
Sorlen Island and the northern anchorage in Ulithi Atoll in late 1944. US Navy
Ulithi consists of 40 small islands, only four of which are inhabited, in an elongated ring around a lagoon about 200 square miles in size and depths of 80 feet to 100 feet.
The atoll was discovered by the Commander of the US Pacific Fleet, Admiral Chester Nimitz, while looking at a map of the area to find a good location for a forward base to support future operations against the Philippines and Japan.
The Japanese had a weather station on the atoll and made limited use of its lagoon as a naval anchorage and seaplane base early in the war, but they withdrew after being attacked by US carrier aircraft. The Japanese saw no strategic value in Ulithi and did not think it could be used against them.
US naval construction battalions, known as “Seabees”, quickly proved them wrong by establishing Ulithi as an advance base almost immediately after landing in late September 1944.
US Navy sailors on Mogmog Island in November 1944. US Navy/Charles Fenno Jacobs
The Seabees extended an abandoned airstrip on Falalop Island to 1,200 yards, erected buoys to mark areas in the lagoon where ships could anchor, established headquarters on Asor Island, and built a boat pool and 100-bed hospital on Sorlen Iceland.
The Navy also relocated the native population of Ulithi to one of the smaller islands, where they lived for the remainder of the war.
Mogmog, the largest and most habitable island, became a much-needed haven for US troops. It had ball fields, a bandstand, a chapel, and a 1,200-seat theater. There was also an ice cream barge that could make 500 gallons of ice cream in one shift. At its peak, the island housed 20,000 men, with around 9,000 of them being there each day.
The lagoon was Ulithi’s most prized feature. Hundreds of ships, including entire groups of carriers, anchored in its waters alongside dozens of seaplanes. There they would be looked after by the small army of naval engineers and logistics personnel assigned to Dienstgeschwader 10.
USS Randolph alongside repair ship USS Jason at Ulithi Atoll on March 13, 1945. Randolph was hit by a Japanese kamikaze on March 11. US Navy
Service Squadron 10 oversaw the rearmament, resupply and repair of Navy ships and aircraft, and otherwise supported the logistical needs of the war effort.
In total, the unit had over 400 ships, including repair ships, tankers, floating dry docks, crane ships, desalination ships, tugboats, floating barracks and floating workshops.
The ships and sailors of Service Squadron 10 allowed the Navy to continue the fight across the expanse of the Pacific. They were called Nimitz’ “secret weapon”.
Ulithi became an extremely important base of operations. Any ship could be repaired – or upgraded enough to return to a larger base – and upgraded there, and troops could rest and recover. Aircraft carriers moored there could continue to launch rescue, reconnaissance and bombing raids.
The liberation of the Philippines and the invasions of Iwo Jima and Okinawa were all launched from Ulithi. It also hosted preparations for the planned invasion of Japan’s home islands.
USS Mississinewa after being hit by a Japanese manned Kaiten torpedo on November 20, 1944. US Navy
By the end of the war, Ulithi was the largest naval base in the world with up to 617 ships. The presence of so many ships also made Ulithi a target.
The Japanese repeatedly tried to attack it with aircraft, mini-submarines and even manned Kaiten torpedoes. On November 20, 1944, the Japanese sank the naval oiler USS Mississineva, killing about 63 sailors and officers.
On March 11, 1945, a long-range kamikaze aircraft struck the carrier USS Randolph, killing 25 men and wounding 106 others. Randolph was repaired at Ulithi and joined the invasion of Okinawa a month later.
Japan even sent its huge I-400-class aircraft-carrying submarines to attack Ulithi. The submarines were under way when Japan surrendered and had to return.
Newfound Relevance
US military hospital ship USNS Mercy near Ulithi Atoll in March 2018. US NavyMCS2 Kelsey L. Adams
Ulithi was largely abandoned after the war, but the atoll is taking on a new meaning as heightened tensions with China make another war in the Pacific more likely.
A forward base would be invaluable in such a conflict, especially since modern guided-missile warships cannot be upgraded at sea.
The need for such a base is compounded by the fact that the US Navy would likely have difficulty repairing warships damaged in battle against major power rivals like China or Russia, according to a report by the Government Accountability Office released last year.
An airfield and high school damaged by Typhoon Maysak on Falalop Island in Ulithi Atoll in December 2015. US Air Force/Osakabe Yasuo
The complexities of modern warship design, coupled with the US divestment of ship repair facilities and the closure of many public shipyards after the Cold War, make repairing battle-damaged ships more of a challenge.
The US Navy is already struggling with a repair backlog. Its surface ships are currently facing maintenance delays of about 4,200 days – effectively reducing the fleet by about 10 ships a year, Navy officials said this month.
With China continuing to build ships, expanding the range of its missile arsenal, and industrial capacity three times that of the US, the Navy would need every advantage it could get.