Joint Army–Navy Assessment Committee

Joint Army–Navy Assessment Committee (JANAC) was a United States inter-service agency set up to analyze and assess Japanese naval and merchant marine shipping losses caused by U.S. and Allied forces during World War II.

Background In January 1943, JANAC was formed by General George Marshall, the Chief of Staff of the U.S. Army, and Admiral Ernest J. King, the Chief of Naval Operations and Commander-in-Chief, United States Fleet (COMINCH), to assess enemy naval and merchant shipping losses during World War II. The objectives of JANAC were as set forth in the following joint Army–Navy directive:

JANAC consisted of representatives of the U.S. Navy, the U.S. Army, and the Army Air Forces, with a joint Army–Navy secretariat, under the chairmanship of Rear Admiral Walter S. DeLany. Following the war, Rear Admiral Jerauld Wright succeeded Delany as JANAC chairman., pp. 236–240

Methodology & results JANAC used the following sources to compile information on Japanese vessel losses during World War II:

Prisoner of War Reports Captured Enemy Documents United States and Allied Intelligence Sources Naval Shipping Control Authority for Japanese Merchant Marine (SCAJAP) Ariyoshi's Final List (Japanese) Ariyoshi's List (Japanese) Shipowners' List (Japanese) Naval Ministry List (Japanese) United States Mine Warfare Report United States and Allied Action Summaries United States Photographic Intelligence United States Strategic Bombing Survey (USSBS) Reports

The assessment of losses, unanimously agreed to by all JANAC members of the committee, was published in 1947, which included:

All Naval vessels known or believed to have been lost. All merchant vessels of 500 or more gross tons known or believed to have been lost.

JANAC provided a detailed chronology of Japanese naval and merchant marine losses cross-indexed in the appendix of its final report, including a separate summary about losses caused by U.S. submarines. JANAC noted that a negligible number of vessels were not assessed because of insufficient information as to the cause of loss.

Sinking Agent Naval Vessels Merchant Vessels Total Vessels No. Tonnage No. Tonnage No. Tonnage TOTALS: 686 1,965,646 2,346 8,618,109 3,032 10,583,755 United States (U.S.): 611 1,822,210 2,117 7,913,858 2,728 9,736,068 Submarines 201 540,192 1,113 4,779,902 1,314 5,320,094 Surface Warships 112 277,817 11 43,349 123 321,166 Army Aircraft 70 62,165 240 639,667 310 701,832 Carrier Aircraft 161 711,236 359 1,390,241 520 2,101,477 Land-based Navy-Marine Aircraft 11 13,402 88 218,718 99 232,120 Army-Navy-Marine Aircraft 9 48,750 23 114,306 32 163,056 Navy Shore Batteries 2 2,770 — — 2 2,770 Mines 19 17,995 247 591,660 266 609,655 Aircraft and Other Agents 26 147,883 32 132,710 58 280,593 Unknown Agents — — 4 3,305 4 3,305 Allied Forces: 45 69,636 73 211,664 118 281,300 United Kingdom (U.K.) 28 50,365 42 87,981 70 138,346 Netherlands 7 8,099 15 57,471 22 65,570 Australia 5 6,892 8 24,910 13 31,802 China — — 3 14,327 3 14,327 Soviet Union 2 1,660 2 8,233 4 9,893 New Zealand 2 2,095 — — 2 2,095 Netherlands and Australia — — 2 8,303 2 8,303 Netherlands and India — — 1 10,439 1 10,439 Australia and India 1 525 — — 1 525 U.S. and Allied Forces: 10 14,864 12 57,923 22 72,787 U.S. and Australia 4 7,550 7 37,072 11 44,622 U.S., Australia, and Netherlands — — 2 16,362 2 16,362 U.S. and U.K. 5 5,102 2 3,500 7 8,602 U.S. and New Zealand 1 2,212 — — 1 2,212 U.S., U.K., and Netherlands — — 1 989 1 989 Marine Casualties: 13 50,338 97 268,948 110 319,286

Legacy

Submarine service JANAC significantly altered wartime estimates for Japanese losses inflicted by the U.S. Navy's submarine service. At the end of World War II, Vice Admiral Charles A. Lockwood and his COMSUBPAC staff had estimated that approximately 4,000 ships had been sunk, totalling 10 million tons lost. JANAC revised this total to 1,314 enemy vessels and 5.3 million tons sunk.; hereafter referred to as Silent Victory JANAC estimates of Japanese losses revised wartime claims downward for most war patrols carried out by the submarine service during World War II as noted in the following table of the revised list of top ten submarines based upon the total tonnage sunk as determined by JANAC.Data compiled from Silent Victory, Appendices E, F, J & K

Ship JANAC figures Wartime Estimates War Patrols Ships Sunk Tonnage Ships Sunk Tonnage Tonnage Ratio 6 21 104,564Blair and Roscoe agree at 100,231 tons. Neither included 1/2 credit for Tosan Maru at 8,666 tons shared with 23 153,800 0.65 8 18 99,901 19 137,200 0.73 12 17 97,579Blair and Roscoe agree at 96,628 tons. Neither included 1/3 credit for Hikoshima Maru at 2,854 tons shared with and 28 197,900 0.48 5 (lost) 24 93,824 31 227,324 0.41 14 23 90,080 26 143,700 0.63 5 21 88,091 21 122,790 0.63 12 (lost) 18 1/3 89,892Blair and Roscoe agree at 88,091 tons. Neither included 1/3 credit for Takane Maru at 10,021 tons shared with and 25⅓ 183,900 0.47 13 15 80,580 19 118,000 0.68 9 15 76,687 17 115,000 0.67 9 (lost) 17 75,473 16 105,800 0.71

JANAC also revised the achievements of individual submarine commanding officers as noted in the following table.Data compiled from Silent Victory, Appendix G

Commanding Officer JANAC figures Wartime Estimates War Patrols Ships Sunk Tonnage Ships Sunk Tonnage Tonnage Ratio Richard H. O'Kane 5 24 93,824 31 227,800 0.41 Slade D. Cutter 4 19 71,729 21 142,300 0.51 Dudley W. Morton 6 (killed in action) 19 54,683 17 100,000 0.55 Eugene B. Fluckey 5 16 95,360 25 179,900 0.53 Samuel D. Dealey 6 (killed in action) 16 54,002 20 82,500 0.65 Reuben T. Whitaker 5 14 60,846 18 111,500 0.55 Gordon W. Underwood 3 14 75,386 14 89,600 0.81 Royce L. Gross 7 14 65,736 13 80,500 0.82 Charles O. Triebel 8 14 58,837 13 83,330 0.71 John S. Coye Jr. 6 14 38,659 14 71,700 0.54

Although JANAC tended to revise downward wartime estimates, one noteworthy exception involved the fifth war patrol of Archerfish (SS-311) under the command of Commander Joseph F. Enright. Archerfish was credited with sinking a 24,000-ton Hiyō-class aircraft carrier during the war, but JANAC determined he had actually sunk the 66,000-ton carrier Shinano, making this the most successful submarine patrol of the Pacific War.Blair. Silent Victory, p. 777 - 780; Appendix I

Battle of Midway JANAC also addressed wartime claims made by the U.S. Army Air Force regarding the sinking of the Japanese aircraft carriers Kaga, Akagi, Hiryū, and Sōryū during the Battle of Midway by giving sole credit to the U.S. Navy.

Joint Army–Navy Assessment Committee

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