"Signals and Instructions" may a be a bit misleading since there is a lot more doctrine (i.e. instructions) here than signals. In my quest for  translated Japanese texts on doctrine and tactics I kept encountering flag signals, something that I find fascinating. Recently I was able to compile the Japanese signal flag inventory and illustrate them in color which, in my opinion, greatly enhances this website.  The title is taken from Sir Julian Corbett's second volume on the Fighting Instructions of the Royal Navy in the sailing ship era; SIGNALS AND INSTRUCTIONS. In a sense the three legs for handling a formation of ships in battle are Doctrine, Tactics and Signalling. Imagine for a moment that before the Battle of Jutland the Royal Navy and the Imperial German Navies had no doctrine for deploying their forces, disengaging in the event their "T" was capped or other maneuvers. Doctrine embues the captains with their commander's wishes should such problem present itself. In the first instance the tactic(s) would be starboard wing or port wing deployment, and in the second a simultaneous turn away. In the first instance the signal would be just three flags from the Royal Navy Signal Book: Equal Speed; Charlie; London. A quick reference to the signal book would reveal Admrial Jellicoe's order. In the latter the same would be true when Admiral Scheer signalled for a reversal of course by a simultaneous turn to starboard (Gefechtskehrtwendung nach steuerbord). He did not do so by spelling out that long phrase but by reference to the IGN's signal book, a green (upper right half) over white flag (lower left half).  


Much has been written of the history and ships of the Imperial Japanese Navy. Though there are books which discuss their doctrine and tactics there has been almost no reference to original sources. The reasons for this omission are numerous. Among them is the wholesale destruction of many of the original documents at war's end. Though more and more items are surfacing much may never be found or recovered. Another reason is the language barrier. Until quite recently most of the material that has survived was inaccessible to those who did not speak, read or write Japanese and of little interest to Japanese language  students generally.  The latter problem is compounded by the fact that the Imperial Japanese Navy had its own, sometimes unique, nomenclature that is dying as those who spoke it die.


This apparent void can be partially filled from a source often overlooked; captured and translated original documents. During the war many documents related to doctrine, tactics and the like fell into the hands of Allied forces. They were translated and distributed to various interested commands.Through the years I have collected many of those documents. 


Here I have created a table of documents that I have. Most are from the wartime period. In many cases I have posted a table of contents for a specific item. Most of the items are too large to post in full. I am always on the lookout for new items.  


There are several excellent English language publications which cover the run up to the war and its first year. I refer specifically to "Japanese Cruisers of the Pacific War" by Eric LaCroix and Linton Wells II, "Kaigun" by David Evans and Mark Peattie, "Sunburst" by Mark Peattie and "Shattered Sword" by Jon Parshall and Tony Tully.


Japanese Navy Research Documents: Tactics, Communications and Technical Matters


Through the years I have accumulated a number of translated Japanese Navy documents as well as lists of many I find of interest. These documents take several forms; hard copy, microfilm and most recently computer links and copies in my computer’s hard drive. This list is an attempt to organize those documents to advise others of their existence. Items marked with an asterisk (*) are in my possession in some form. Tables of contents of most of these items are linked here as indicated in blue. All eventually all should be.  


Tactics and Doctrine

The documents listed here are translations of original Japanese Tactics and Doctrine materials. Unless otherwise noted these are hard copies and microfilm:

Combined Fleet Doctrine, Book 1 (Combat) Combined Fleet Ultrasecret Standing Order #81, 5 December 1943, 55pp*Combined Fleet Doctrine

Cruiser Doctrine, Second Fleet Commander Second Fleet Ultrasecret Standing Order #5 22 January 1944, 17pp*Cruiser Doctrine

Cruiser Division 5 Secret Order #12, Part 7 (gunfire distribution tables) 18 December 1942, 2pp*

Diversion Attack Force Doctrine, Commander Second Fleet Ultrasecret Standing Order #2, 1 January 1944, 60pp*Diversion Attack Force Doctrine

Night Force Doctrine, Commander Second Fleet Ultrasecret Standing Order #1, 1 January 1944, 15pp*Night Force Doctrine Pt. 1

Night Force Doctrine, Revised, Commander Second Fleet Ultrasecret Standing Order #15 1 May 1944, 12pp*Night Force Doctrine Pt. 2

Night Force Doctrine, Commander Fifth Fleet Ultrasecret Standing Order #15 August 1944, 16pp*Night Force Doctrine 5th Fleet

Carrier Division 4 Doctrine; Commander Carrier Division 4 Ultrasecret Standing Order #20, 27 November 1941, 16pp*Carrier Division 4 Doctrine 11-41

Research on Mobile Force Tactics; Yokosuka Kokutai Serial #45 20 May 1943, 38pp*Research on Mobile Force Tactics

First Mobile Fleet Doctrine; Commander First Mobile Fleet Ultrasecret Standing Order #1, 25 March 1944, 19pp*First Mobile Fleet Doctrine

Signal Appendix First Mobile Fleet Doctrine; Commander First Mobile Fleet Ultrasecret Standing Order ##17, 23 August 1944, 47pp*Signal Appendix Mobile Fleet Doctrine

Destroyer Squadron Doctrine, Second Fleet; Commander Second Fleet Ultrasecret Standing Order #20, 18 December 1943 40pp*Destroyer Doctrine

Destroyer Squadron Procedure, Second Fleet, Commander Second Fleet Ultresecret Standing Order #21, 18 December 1943 85pp*Destroyer Procedure

Battle Lessons Learned in the Greater East Asia War (Torpedoes) Vol 6 Torpedo School Publication 5 Nov. 1943*Battle Lessons, Torpedoes vol 6; Nov. 1943

Battle Lessons Learned in the Greater East Asia War (Torpedoes) Annex 1 to Vol 6 Torpedo School Publication 5 Nov. 1943*Battle Lessons, Torpedoes Annex to vol 6 MTBs



Navy Operation Plans and Orders

Full translation of original files of operation orders, orders, memoranda and serials dealing with Navy operation plans issued by Combined Fleet, 1 and 2 Diversion Attack Forces, 1 Mobile Fleet, 2 and 5 Fleets and other commands

Orders related to SHO-GO Operation (6 Items)*Sho-go Operations Orders

Combined Fleet Operations Orders, Orders and Serials, 1941-4 (43 items)*Combined Fleet Operations Orders 1941-4

Northern Force Operations Orders, Serials, etc. (10 items)*Northern Force Operations Orders

Northern Force Doctrine for Interception Zone Operations (4 items)*Northern Force Doctrine for Interception Zone Operations


Signals and Communications

Operational History of Naval Communications; December 1941-August 1945. Japanese Monograph 118. This covers most aspects of Japanese radio communications at various stages of the war including fleet broadcasts, communications plans for various operations, radio outfits in ships and aircraft and the like. (I have hard copy; 407 pp)*

Wireless and Flashing Light: The Japanese had a version of the Morse Code that followed the Kana. There is a very good on line site: which describes various digressions from the standard Morse, including the Japanese version. It has a table with three columns: Roman letter or Arabic number; kata kana; code (dot/dash). Since there are more kana than Arabic numbers and Roman letters combined there are some blanks in the Roman letter/Arabic number column. You can work past the more arcane parts of the article and focus on the table, or read the entire article! It even describes how they deal with diacriticals. I have a hard copy of this article*


Semaphore: The Japanese Semaphore uses the kana. There are several sites with their semaphore. One I use is It is a bit tricky getting into and the translation program is word for word, a bit tough until you get used to it. If you type the link on Google and hit “translate” this page prompt it should give you the English language page. I have a hard copy of this article in English*

Signal Flags and Signal Books: Most of the references in the section “Tactics and Doctrine” have signals with the “Signal Appendix to Mobile Fleet Doctrine” being the most comprehensive (Signal Appendix Mobile Fleet Doctrine). I do not have the General Signal Book. The Japanese divided their signal flags into two categories, which were, in turn, further divided into five sub sets: (Japanese Navy Signal Flags):


Symbol and Number Flags:

International Letter Flags: The same 26 International Letter Flags in use today.

Number Flags: Ten Special Navy number flags representing the numbers 0-9


Special Navy Flags and Pennants

Special Naval Maneuver flags: Ten triangular pennants which include the three international repeaters. These pennants perform the same function as the modern corpen, turn, formation, etc.

Ships, Fleets and Division flags. Fourteen pennants including all of the International numeral pennants. These correspond roughly to the modern division, squadron, etc flags and pennants. 

Special Classification Flags: Nine pennants which correspond to the modern interrogatory, prep, etc. One of these pennants is also the international answer pennant.



I have color plates which illustrate all of the flags and an accompanying text with their meaning, reading and kana use. In addition to the color plates I have merged many of the signals in the documents in “Tactics and Doctrine” into a “signal book". This book contains an explanation of the kana and its use in Japanese signaling. That explanation is an appendix to the “signal book”.


Here is that Signal Book:

Complete Signal Book


Signal Flags Used by Japanese Naval and Merchant Ships; ATIS Research Report #96, 15 June 1945, 12pp hard copy and pdf . Most of the flags and pennants in this book are local or weather type signals not found in the International Signal Flag set or the Special Navy Signal Flag set. Some are local in character. Includes section on speed cones.* 

Recognition Signals: Wartime Regulations for Identification of Friendly Forces, Navy Ministry Military Ultrasecret Serial 1183, 20 June 1944, 15pp*Wartime Regulations for Recognition of Friendly Forces, 20 June 1944

Battle Lessons, Observations and outline of progress of Communications in Battle of Attu Island (Komandorski). This is a complete traffic analysis of USN traffic intercepted by the Japanese during the Battle of Komandorski. It is a good look inside their at sea communications traffic analysis.* (hard copy and microfilm) Battle Lessons (Communications) Battle of Komandorski