Operation Isolator

'Isolator' was the US overall designation of attacks by US Navy surface vessels and USAAF warplanes on Japanese positions and shipping along the south-western coast of Japanese-occupied China (1944/45).

The object of these operations was to isolate the various Japanese garrisons and so prevent either their reinforcement and supply, or their maritime evacuation for service elsewhere.

On 20 May 1944, for example, Consolidated B-24 Liberator heavy bombers of Major General Claire L. Chennault’s US 14th AAF bombed Takao on Formosa and a convoy approaching this port, sinking or damaging several of the Japanese ships. The gunboat Hashidate took one of the damaged ships, Tsukuba Maru, in tow but on 22 both of these vessels were sunk by the US submarine Picuda.

On 16 October 1944, Liberator bombers of the 14th AAF attacked Japanese shipping to the south-west of Hong Kong, and sank the torpedo boat Hato and one merchant vessel.

On 12 January 1945 carrierborne aircraft of Vice Admiral William F. Halsey’s Task Force 38 attacked targets in Japanese-occupied Vichy French Indo-China, and to the north of Qui Nhon the Japanese HI.86 was destroyed when the light cruiser Kashii, frigate Chiburi, corvettes Kaibokan 17 and Kaibokan 19, three tankers and one transport were sunk, and Kaibokan 23, Kaibokan 51 and 11 other ships were damaged. In a separate attack, the frigates Daito and Ukuru, corvette Kaibokan 27 and landing ships T-149 and T-137 were damaged. Three ships of the SASI.40 convoy were sunk off Vung Tau, as too, off Cape Padaran, were five transports of the SATA.05 convoy, together with the corvettes Kaibokan 35 and Kaibokan 43, minesweeper W-101 and patrol boat No 103. Off Camranh Bay, the submarine-chaser Ch-41 was sunk and Ch-34 damaged. Near Saigon, the landing ship T-140 and six merchant vessels were sunk and T-131 and two freighters damaged.

On 15/16 January 1945 carrierborne aircraft of TF38 attacked shipping along the coasts of Hainan, Hong Kong and China, and also off Formosa. On 15 January the destroyer Hatakaze, escort destroyer Tsuga, landing ship T-14 and two merchant vessels were sunk, and the minelayer Maroshima and two other vessels damaged. On the following day the task force’s aircraft sank eight ships and damaged the oiler Kamoi, escort destroyers Hasu, Shinnan, Nomi and Daito, corvette Kaibokan 60 and landing ship T-108.

Between 3 and 6 April 1945 USAAF aircraft attacked Japanese shipping along the coast of southern China, sinking the frigate Manju and damaging the escort Kaibokan 52 at Hong Kong.

Between 6 and April 1945 North American B-25 Mitchell medium bombers of the USAAF attacked the HOMO.03 convoy off Amoy, sinking the corvettes Kaibokan 1 and Kaibokan 134, and damage the destroyer Amatsukaze irreparably. On 7 April US aircraft sank the Japanese fleet oiler Kamoi at Hong Kong. On 8 April the Japanese destroyer-escort Habushi was damaged by an air-laid mine off Woosung.

On 16 May 1945 the US programme of aerial mining in the China theatre, which began on 16 October 1943, reached its end. B-24 Liberators of the US 14th AAF had flown 255 sorties, with 209 aircraft dropping 976 mines, and Boeing B-29 Superfortress heavy bombers of the 20th AAF had flown 22 sorties, laying 263 mines and losing four aircraft. Altogether, 825 magnetic, 182 acoustic and 232 contact mines had been laid in the areas of Haiphong, Hong Kong, Takao, Shanghai, Yulinkan on Hainan island, Canton, Kiirun Ko and the Yangtse river.