Patrol 1

8 Feb 1942 - 4 Apr 1942

第二号海城丸 Kaijo Maru No. 2 Go

Patrol 2

28 Apr 1942 - 17 Jun 1942

No sinkings

Patrol 3

8 Jul 1942 - 30 Aug 1942

Patrol 4

2 Oct 1942 - 23 Nov 1942

Patrol 5

14 Dec 1942 - 19 Jan 1943

Patrol 6

11 Feb 1943 - on or about 5 Mar 1943 - Grampus lost

Current research credits Grampus with sinking 1 ship of 8,636 tons. These figures are the same for JANAC and Alden-McDonald

SORG credits Grampus with 6 ships and 45,400 tons sunk.

Japanese Naval and Merchant Ship Losses - JANAC on the NHHC website

JANAC on the Hyperwar website - https://www.ibiblio.org/hyperwar/Japan/IJN/JANAC-Losses/JANAC-Losses-6.html

SORG- http://archive.hnsa.org/doc/subreports-sorg.htm (Excel spreadsheet download)

Archives of the Pacific Fleet Submarine Museum (PFSM)

War Patrol Reports - USS Grampus

Monthly Losses of Combatant and Non-Combatant Vessels

太平洋戦争時の喪失船舶明細表（汽船主体）- Lost Vessel table during the Pacific War (merchant vessels)

Alden, John D., and McDonald, Craig R. - U.S. & Allied Sub Successes in the Pacific & Far East during WWII - Fourth Edition, 2009

Cressman, Robert - The Official Chronology of the U.S. Navy in World War II, Naval Institute Press, 2000.

Wrecksite - https://www.wrecksite.eu/wrecksite.aspx

Miramar Ship Index - https://www.miramarshipindex.nz/

Imperial Japanese Navy Page - http://www.combinedfleet.com/

Wikipedia Japan - https://ja.wikipedia.org/wiki/

Japan Center for Asian Historical Records - National Archives of Japan - https://www.jacar.go.jp/index.html

Official U.S. Navy Photos - Naval History & Heritage Command

Archives of the Pacific Fleet Submarine Museum (PFSM)

Imperial Japanese Navy Page - http://www.combinedfleet.com/

Japanese Merchant Ship photos - Wrecksite - copyright owners retain all rights. Photos used on this site will be taken down should the owner request their removal.