were a numbered series of World War II trade convoys between Japan and Singapore. Merchant ships from Moji and Kaibōkan from Sasebo formed southbound convoys in Imari Bay to carry supplies for the Burma Campaign. Northbound convoys transported food, petroleum, and raw materials to Japan from the captured European colonies of the Dutch East Indies, French Indochina, and British Malaya and Burma. These convoys were initiated in mid-1943 to protect fast, high-value tankers and troopships from the improved effectiveness of Mark 14 torpedoes carried by United States submarines.
Convoy routing was through the East China Sea, Formosa Strait, and South China Sea. Ships often joined or left convoys at the Formosan ports of Takao and Keelung, at the Mako naval base in the Pescadores, and at the Vietnamese ports of Cape Saint Jacques and Cam Ranh Bay. Some convoys stopped at Manila until MATA and TAMA feeder convoys between MAnila and TAkao enabled Hi convoys to avoid United States submarine wolfpacks in the Luzon Strait by hugging the Asian coast between Hainan and Shanghai.[1]
| Number | Direction | Imari Bay[2] | Singapore | Notes | |
|---|---|---|---|---|---|
| Hi-1 | South | 10 July 1943 | 19 July 1943 | ||
| Hi-2 | North | 3 August 1943 | 23 July 1943 | ||
| Hi-3 | South | 19 July 1943 | 1 August 1943 | Attacked by on 22 July[3] | |
| Hi-4 | North | 15 August 1943 | 5 August 1943 | ||
| Hi-5 | South | 7 August 1943 | 19 August 1943 | ||
| Hi-6 | North | 3 September 1943 | 24 August 1943 | ||
| Hi-7 | South | 25 August 1943 | 6 September 1943 | ||
| Hi-8 | North | 21 September 1943 | 11 September 1943 | ||
| Hi-9 | South | 10 September 1943 | Terminated 21 September 1943 at Cape Saint Jacques | ||
| Hi-10 | North | 9 October 1943 | Originated 28 September 1943 at Cape Saint Jacques | ||
| Hi-11 | South | 25 September 1943 | 4 October 1943 | ||
| Hi-12 | North | 21 October 1943 | 10 October 1943 | ||
| Hi-13 | South | 12 October 1943 | 30 October 1943 | ||
| Hi-14 | North | 16 November 1943 | 3 November 1943 | Attacked by on 8 November[4] | |
| Hi-15 | Did not sail | ||||
| Hi-16 | Did not sail | ||||
| Hi-17 | South | 28 October 1943 | 11 November 1943 | ||
| Hi-18 | North | 28 November 1943 | 15 November 1943 | ||
| Hi-19 | Did not sail | ||||
| Hi-20 | Did not sail | ||||
| Hi-21 | South | 20 November 1943 | 14 December 1943 | ||
| Hi-22 | Did not sail | ||||
| Hi-23 | South | 1 December 1943 | 14 December 1943 | ||
| Hi-24 | North | 4 January 1944 | 19 December 1943 | ||
| Hi-25 | South | 11 December 1943 | 21 December 1943 | ||
| Hi-26 | North | 26 December 1943 | |||
| Hi-27 | South | 21 December 1943 | 2 January 1944 | Attacked by on 27 December[5] | |
| Hi-28 | North | 17 January 1944 | 8 January 1944 | ||
| Hi-29 | South | 31 December 1943 | 15 January 1944 | ||
| Hi-30 | North | 12 February 1944 | 19 January 1944 | ||
| Hi-31 | South | 11 January 1944 | 20 January 1944 | ||
| Hi-32 | North | 4 February 1944 | 25 January 1944 | ||
| Hi-33 | South | 10 January 1944 | 23 January 1944 | ||
| Hi-34 | North | 10 February 1944 | 27 January 1944 | ||
| Hi-35 | Did not sail | ||||
| Hi-36 | Did not sail | ||||
| Hi-37 | South | 20 January 1944 | 29 January 1944 | ||
| Hi-38 | North | 13 February 1944 | 2 February 1944 | ||
| Hi-39 | South | 26 January 1944 | 9 February 1944 | ||
| Hi-40 | North | 13 February 1944 | Dispersed 24 February under attack by and [6] | ||
| Hi-41 | South | 1 February 1944 | 11 February 1944 | ||
| Hi-42 | North | 28 February 1944 | 16 February 1944 | ||
| Hi-43 | South | 11 February 1944 | 3 March 1944 | ||
| Hi-44 | Did not sail | ||||
| Hi-45 | South | 16 February 1944 | 27 February 1944 | ||
| Hi-46 | Did not sail | ||||
| Hi-47 | South | 21 February 1944 | 5 March 1944 | Attacked by on 4 March[7] | |
| Hi-48 | North | 25 March 1944 | 11 March 1944 | Attacked by on 18 March[8] | |
| Hi-49 | South | 23 February 1944 | 11 March 1944 | ||
| Hi-50 | North | 8 April 1944 | 15 March 1944 | ||
| Hi-51 | Did not sail | ||||
| Hi-52 | Did not sail | ||||
| Hi-53 | South | 8 March 1944 | 18 March 1944 | ||
| Hi-54 | North | 29 March 1944 | Merged with Hi-56 | ||
| Hi-55 | South | 19 March 1944 | 3 April 1944 | Attacked by on 2 April[9] | |
| Hi-56 | North | 24 April 1944 | 8 April 1944 | Merged with Hi-54 | |
| Hi-57 | South | 3 April 1944 | 16 April 1944 | 1 April departure delayed by storm | |
| Hi-58 | North | 3 May 1944 | 21 April 1944 | Submarine USS Robalo seen by aircraft from Japanese aircraft carrier Kaiyō and damaged by convoy escort 24 April 1944 | |
| Hi-59 | South | 20 April 1944 | Terminated 2 May 1944 at Manila | ||
| Hi-60 | Did not sail | ||||
| Hi-61 | South | 3 May 1944 | 18 May 1944 | ||
| Hi-62 | North | 8 June 1944 | 23 May 1944 | ||
| Hi-63 | South | 13 May 1944 | 27 May 1944 | Attacked by on 24 May[10] | |
| Hi-64 | North | 15 June 1944 | 6 June 1944 | ||
| Hi-65 | South | 29 May 1944 | 12 June 1944 | Attacked by and on 2 June[11] | |
| Hi-66 | North | 26 June 1944 | 17 June 1944 | ||
| Hi-67 | South | 22 June 1944 | 9 July 1944 | Attacked by on 29 June[12] | |
| Hi-68 | North | 3 August 1944 | 14 July 1944 | Attacked by, and on 26 July[13] | |
| Hi-69 | South | 13 July 1944 | 31 July 1944 | ||
| Hi-70 | North | 4 August 1944 | 15 August 1944 | ||
| Hi-71 | South | 8 August 1944 | 1 September 1944 | Attacked by,,,, and | |
| Hi-72 | North | 28 September 1944 | 6 September 1944 | Attacked by, and on 12 September[14] | |
| Hi-73 | South | 25 August 1944 | 5 September 1944 | ||
| Hi-74 | North | 23 September 1944 | 11 September 1944 | Attacked by on 16 September[15] | |
| Hi-75 | South | 8 September 1944 | 22 September 1944 | Attacked by on 18 September[16] | |
| Hi-76 | North | 26 October 1944 | 2 October 1944 | Hi-76A departed Singapore 12 October | |
| Hi-77 | South | 1 October 1944 | 12 October 1944 | Attacked by,, and on 6 and 7 October[17] | |
| Hi-78 | North | 2 November 1944 | 20 October 1944 | ||
| Hi-79 | South | 26 October 1944 | 9 November 1944 | Subsidiary Hi-79A formed on 6 November 1944 | |
| Hi-80 | North | 2 December 1944 | 17 November 1944 | ||
| Hi-81 | South | 14 November 1944 | 4 December 1944 | Attacked by, and on 15 and 17 November[18] | |
| Hi-82 | North | 9 January 1945 | 12 December 1944 | Attacked by on 22 December[19] | |
| Hi-83 | South | 25 November 1944 | 13 December 1944 | Attacked by on 3 December[20] | |
| Hi-84 | North | 13 January 1945 | 26 December 1944 | ||
| Hi-85 | South | 19 December 1944 | Terminated 4 January 1945 at Cape Saint Jacques | ||
| Hi-86 | North | 10 February 1945 | Originated 9 January 1945 at Cape Saint Jacques; attacked by Task Force 38 on 12 January[21] | ||
| Hi-87 | South | 31 December 1944 | 23 January 1945 | Attacked by Task Force 38 on 16 January[22] | |
| Hi-88 | North | March 1945 | 20 January 1945 to 18 March 1945 | Sailed as ten independent small convoys; Hi-88H attacked by on 23 February, and Hi-88I by and on 20 and 21 March[23] | |
| Hi-89 | South | 24 January 1945 | 8 February 1945 | ||
| Hi-90 | North | 4 March 1945 | 15 February 1945 | ||
| Hi-91 | South | 26 January 1945 | 8 February 1945 | ||
| Hi-92 | North | 11 March 1945 | 18 February 1945 | Attacked by on 25 February[24] | |
| Hi-93 | South | 29 January 1945 | 12 February 1945 | ||
| Hi-94 | North | 14 March 1945 | 23 February 1945 | ||
| Hi-95 | South | 31 January 1945 | 14 February 1945 | ||
| Hi-96 | North | 22 February 1945 | 13 March 1945 | Attacked by on 27 February | |
| Hi-97 | South | 7 February 1945 | 15 February 1945 | ||
| Hi-98 | North | 27 February 1945 | Single ship convoy Ryoei Maru sunk by [25] |