Monday, January 12, 2015

Second kaiten attack at Ulithi

Throughout the first couple of weeks of January 1945, my dad's repair ship, USS Hector, brought the subchaser, USS PC-1130, alongside for emergency repairs. The patrol craft's sonar equipment had been damaged and required Hector's attention. Even while receiving repairs, however, the ship still carried on patrol duties as required. One of the big concerns was the ever-present danger of another attack like the one on November 20, 1944. In that attack, Japanese submarines launched human torpedoes, or "kaitens," toward the anchored fleet, destroying USS Mississinewa and killing 60 of her crewmen.

Nearby, on today's date, the ammunition ship, USS Mazama, which had only days before arrived at Ulithi with a full load of cargo, sighted a suspicious moving object off its starboard side. Moments later, around 7:00 AM, an explosion rocked the ship, causing severe flooding. It had been attacked by a kaiten.

Around 9:00 AM, the PC-1130 was ordered underway from the Hector to patrol for enemy midget subs within the harbor. At 10:15, the subchaser witnessed an explosion about 200 yards away. Although its sonar was temporarily knocked out in the explosion, nevertheless the subchaser immediately altered course to intercept and ram the sub if it surfaced. As it passed over the spot, it dropped 3 depth charges for good measure. Leaving follow-up work for an arriving destroyer, the PC-1130 proceeded on outside the lagoon to continue its patrol.

Meanwhile, the damage and flooding on the Mazama had caused the ship to list. Immediately, pumping was started to handle the flooding. For a while, the crew thought the ship may have to be beached to avoid sinking, so it got underway for land. However, tugboats and other fleet vessels came to assist the struggling ship. A diving crew from Hector also arrived to inspect the damage and effect temporary repairs. Hector's divers confirmed that the explosion had indented a significant section of the ship, and its seams had separated. The next day, a repair party from Hector caulked and plugged the open seams enough to pump out the water.

The Japanese submarine that had launched the attack against the Mazama was the I-36, the same ship that launched its manned torpedoes against Ulithi the previous November. This time, a Navy PBM patrol bomber spotted one of the attacking kaitens in the lagoon and destroyed it by dropping 4 depth charges. But the other 3 managed to attack targets within the harbor. In addition to damaging the Mazama, killing 1 and seriously injuring 7, another of the kaitens sank the infantry landing craft, LCI-600, killing 3.

Temporary repairs to the Mazama were completed by March 6 when the ship steamed for San Francisco for permanent repairs. By June, she was back in the Philippines with 5,000 tons of ammunition. In July, she entered San Pedro Bay where she remained through the end of the war. After participating in the American Occupational Force of the Japanese Home Islands, she enjoyed a long period of service until her permanent decommissioning in 1970. The USS Mazama received 5 battle stars for her WWII service.

PC-1130 also survived the war, and after spending some time in reserve, was transferred to France and then to South Vietnam. She was struck from the Naval Register in 1965.

The I-36 continued to see service in the Japanese fleet, surviving until the surrender in September 1945. On April 1, 1946, as part of "Operation Roads End," the I-36 was towed to sea and scuttled.

Sources: USS PC-1130 War Diary, January 1945; USS Mazama War Diary, January 1945


  1. Thanks for the discussion of this little-known kaiten attack. My father was First Lieutenant/cargo officer aboard Mazama at the time of this attack. Outside of the copy of the official report he kept in his personal papers, this is one of the better accounts of the action I have seen.

  2. Thanks for sharing your comment, Bill. Your dad must have some amazing stories to tell. I hope you've been able to preserve them.