Japanese Fortifications and Defense Organization in World War 2

Intro

Time to take a look at some Japanese field fortifications and defense measures. Note that in this case I used mostly sources from US military intelligence in World War 2. Unlike the Atlantikwall video this video is about the small scale units, hence you will see an individual bunker and also layouts for company and platoon defenses. Note that every country had some distinctive features, but the general layout were to a certain degree quite similar, if we consider this statement from the in publication Japanese in Battle from August 1944:
“Examples of typical defence layouts, from platoon to battalion positions, are shown at Appendix ‘ A ‘. They show no remarkable difference in principle from our own layouts.” (General Headquarters, India – Military Intelligence Directorate: Japanese in Battle – Second Edition, August 1944, p. 5)

Attitude towards defense

The Japanese had quite a negative attitude towards defensive combat, similar to the German Army, thus both addressed defense usually only in limited amount, but nevertheless both proved quite capable and dangerous in defensive operations and improved their training and manuals throughout the war. (War Department: Handbook on the Japanese Military Forces, 15 September 1944, p. 99; Das Dogma der Beweglichkeit. Überlegungen zur Genese der deutschen Heerestaktik im Zeitalter der Weltkriege, in: Bruno Thoß, Erich Volkmann (Hrsg.), Erster Weltkrieg – Zweiter Weltkrieg. Ein Vergleich. Krieg –Kriegserlebnis – Kriegserfahrung in Deutschland. Paderborn u.a. 2002, S. 143-166)

In General, besides their attitude towards defensive Combat the Japanese were renowned for both their elaborate defensive fortifications and their tenacity in defense. One area they were clearly lacking though, was the use of mines. But let’s take a closer look at those issues.

No Amateurs – Well constructed Bunkers

The Japanese constructed their bunkers usually from logs and earth. The logs were interwoven and strongly attached to each other. To strengthen the roofs of bunkers against indirect fire, they used alternating layers of logs and earth. This provided excellent protection and usually gave full protection against mortar and light artillery fire. (War Department: Tactical and Technical Trends, No. 21, March 25, 1943, p. 17)
Furthermore, for the Buna area (southeastern New Guinea) it was stated that:
“in addition, the bunkers had been planned and built for just this purpose long before the campaign actually started, and the quick jungle growth, sprouting up over the earthworks, gave first-class natural camouflage.” (War Department: Tactical and Technical Trends, No. 21, March 25, 1943, p. 17)
[Buna-Gona Battle (1942/1943)]

Tenacity

The tenacity and fanatism of the Japanese troops in World War II is well known and Field Marshal Slim wrote about the individual Japanese soldier the following:
“He fought and marched till he died. If 500 Japanese were ordered to hold a position, we had to kill 495 before it was ours – and then the last five killed themselves.” (Slim, William: Defeat into Victory, p. 615)

After all the Japanese doctrine and training put a strong emphasis on morale factors and tenacity. (Drea, Edward J.: In Service of the Emperor, p. 64) An US Army engineer remarked about the campaign in Buna the following:
“It would be impossible to overstress the tenacity with which the Jap[ane]s[e] clung to their prepared positions. Grenades, and ordinary gun and mortar fire were completely ineffective. There were many instances (not isolated ones) where dugouts were grenaded inside, covered with gasoline and burned, and then sealed with dirt and sand,—only to yield, 2 or 3 days later, Jap[ane]s[e] who came out fighting.” (War Department: Tactical and Technical Trends, No. 21, March 25, 1943, p. 17)

Mines

Although, the Japanese employed various ruses like dummy snipers and simulating friendly fire by synchronizing their own artillery with the artillery of the attackers, but their capabilities in mine warfare was quite limited for most of the war..( War Department: Tactical and Technical Trends, No. 21, March 25, 1943, p. 18; War Department: Intelligence Bulletin Vol III, No. 4, December 1944, p. 13)
In 1944 according to the Intelligence Bulletins this changed:
“Instructions recently issued to some Japanese troops in the far Southwest Pacific areas attempt to establish definite uniformity and improvement in the employment of land mines.” (War Department: Intelligence Bulletin Vol III, No. 4, December 1944 , p. 13)

Yet, it is also noted that:
“In this respect, the instructions as a whole are very general. They tell “what” should be done, but neglect to tell “how” the minelaying should be carried out. It is possible that, like many such Japanese orders, the details and the operational technique are left to the discretion of subordinate commanders.” (War Department: Intelligence Bulletin Vol III, No. 4, December 1944, p. 15)

Now, general instructions usually require a highly trained force, yet in 1944 all of the Axis members had lost most of the their best trained units.

Example: Beach Defenses Talisay-Tanke

Now, let’s see what the US engineers noted about a late war Japanese beach defense. In March 1945 US troops landed on the Talisay beach, where the Japanese had established an elaborate defensive system, but since the beach was undefended the site was mostly intact and could be examined by US troops. (HQ Eight Army – Engineer Section: Intelligence Bulletin No. 3, May 1945, p. 2-19) Since the conclusions of the report are rather short and cover mines, fortifications and ditches of a late war Japanese beach defense, I will quote directly from the report:

“1. Japanese employment of bombs and shells as improvised AT and AP mines was excellent. Their effectiveness was limited only by poor concealment, failure to arm some shells, and failure to cover them with fire. The75 mm shells used would have been particularly effective against personnel if they had been properly concealed.“
[AT – Anti-Tank; AP – Anti-Personnel]
(HQ Eight Army – Engineer Section: Intelligence Bulletin No. 3, May 1945, p. 18)

“2. The AT ditches were adequate to stop our medium tank. The log and rail barriers probably would not have stopped medium tanks or bulldozers completely, but would have provided sufficient delay to prevent armor over-running a position covered by adequate AT and small arms fire, and made the tanks good targets for AT weapons. “
(HQ Eight Army – Engineer Section: Intelligence Bulletin No. 3, May 1945, p. 18)

“3. Most of the firing positions and shelters afforded protection only against small arms fire, blast, shell and bomb fragments, and light mortar fire. None of the emplacements furnished protection from direct hits of 100 pound bombs or naval shell fire. Considered as light emplacements, the works demonstrated excellent improvisation and effective utilization of locally available materials by the Japanese.”
(HQ Eight Army – Engineer Section: Intelligence Bulletin No. 3, May 1945, p. 18)

Defensive Positions

Now, in this part, we will take a closer look at defensive positions. Once the command is given to occupy a position and setup defensive preparation the development was usually prioritized the following way: 1) Establishing the important points in the main line of the resistance, 2) Determining and development of the fields of fire and observation posts, 3) Setting up obstacles for the main line of resistance and 4) the development of communication trenches and personnel shelters. (War Department: Handbook on the Japanese Military Forces, 15 September 1944, p. 101-103) Let’s take a closer look at the development of a company position.

To give you some time-frame for orientation it is noted that:
„The division usually has from about 3 hours to a half day to complete its organization of the ground. Three hours is considered the minimum required to organize a rudimentary system of trenches and obstacles along the main line of resistance. The timework unit in engineering calculations is the 12-man squad which is considered capable of digging about
25 yards [23 metres] of standing fire trench in a little over 3 hours.” (War Department: Handbook on the Japanese Military Forces, 15 September 1944, p. 101)

Typical Company Position

Now, here you can see a company position after about 2 hours of work. Each of the areas is for one platoon, the firing trenches are for individual squads. The heavy machine gun is deployed along the support position. It is directed in a diagonal line, the same as neighboring units thus the cover is interlocked. After another 4 hours, the firing trenches of the squads should be connected forming a single line.(War Department: Handbook on the Japanese Military Forces, 15 September 1944, p. 102, Figure 86; & p. 100 (HMG))

The position after a week of construction, whereas a week is 56 hours of work. The caption of the illustration reads as follows:
“Squad positions will be enlarged [to] standing trenches. The communication trenches will be deep enough for crawling, and the shelters will be of light construction accommodating 6 men. Only the machine gun shelters will be built to resist 150-mm howitzer fire. The wire entanglements beyond the front-lines will be 8 meters in depth.” (War Department: Handbook on the Japanese Military Forces, 15 September 1944, p. 102, Figure 87)

Now, the same position after about 4 weeks of construction time, would be improved considerably. There would be another layer of wire in the front. And also some basic wiring on the flanks. Additionally, the trenches would be connected in a sophisticated system with adjacent units too. The individual shelters would be covered with roofs. Furthermore, although I am not completely certain, since there is no legend on the original figure, there would be tunnels or covered trenches connecting to the rear area. Looks a bit different than those 3 ovals from the start. (War Department: Handbook on the Japanese Military Forces, 15 September 1944, p. 103, Figure 88; see also Japanese in Battle)

A “Platoon” Defense Position in Burma

Now, let’s take a closer look at a platoon position from Burma. As a quick reminder a company usually consists of three platoons, so basically we take a look at a unit one level deeper.
As you can see it has a circular pattern. In the rear area there is a larger shelter with sleeping accommodation. The circular endings of the trenches are foxholes, whereas each has a one-man-dugout nearby, which had an earth and timber cover. Furthermore, there was a MG position that was well covered too. The report notes that the dugouts near each foxhole and three-bay machine gun position were the two interesting features. So, let’s take a look at the MG position.
(War Department: Intelligence Bulletin Vol III, No. 4, December 1944, p. 15)
(General Headquarters, India – Military Intelligence Directorate: Japanese in Battle – Second Edition, August 1944, p. 24)

MG Position

So, this is a Japanese Three-Bay Light Machine gun position in Burma from the side. As you can see the roof is constructed with several logs and reinforced with earth. The machine gun would be placed here. Now, why was it called “three-bay”, well let’s look at it from the front. As you can clearly see, the supporting logs divided the firing slit into three areas. And by the way, this is a type 96 Japanese light machine gun and not a British Bren, they look similar, but there is a clear difference between those two, which might not be so obvious.
Problem with the Numbers
Now, let’s go back to the Platoon position, because there is one problem I have encountered, which I couldn’t find a proper answer too. Basically, the numbers don’t add up.

The shown position is according to the description for a platoon. But the problem is that a rifle platoon of an infantry company of an “A” or “B” type division had 3 LMGs and furthermore 62 or 54 men. Now, there is only one position for an LMG, but also the area is quite small for 54 let alone 62 men. Although, the number of foxholes and LMGs would match almost exactly the layout of a rifle section. But I doubt such an error would occur, especially since this layout was reprinted in two different military intelligence publications.
Hence, I must assume that the platoon was far below full strength, but still I am confused that this isn’t noted in the report. But of course there is always the chance that I missed something or made an error. If anyone knows more, please let me know in the comments.

Summary

To summarize, although the Japanese had a serious distaste for defensive combat, their ingenuity and improvisation skills allowed them to construct various kinds of excellent field fortifications and defensive systems. Although their ability to lay sophisticated mine fields was limited for most of the war, the Japanese Army took actions to counter this problem and probably would have reached similar capabilities as other forces.

Now, a little public service announcement. I originally wanted to do something about naval tactics in the non-world war era, but since I got a bit sick and thus my mind could only operate at limited capacity, I switched to this easier topic, after all, I am mostly a land-rat from the modern era. So stay tuned, I plan to cover nearly every era of military history, major battle and much much more. Since I get quite a lot of repeating question about what topics I will cover, you might want to check out the frequently asked questions on my homepage.

Sources

TM-E-30-480 – War Department: Handbook on the Japanese Military Forces, 15 September 1944

War Department: Intelligence Bulletin Vol II, No. 7, March 1944

War Department: Intelligence Bulletin Vol II, No. 8, April 1944

War Department: Intelligence Bulletin Vol III, No. 4, December 1944

HQ Eight Army – Engineer Section: Intelligence Bulletin No. 3, May 1945

General Headquarters, India – Military Intelligence Directorate: Japanese in Battle – Second Edition, August 1944

War Department: Tactical and Technical Trends, No. 21, March 25, 1943

Field Manual 5-15, Field Fortifications, August 1968

Drea, Edward J.: In Service of the Emperor

Atlantic Wall – Example of a Coastal Defense Position (Atlantikwall)

Background

The Atlantic Wall or “Atlantikwall” in German was an extensive system of coastal defences and fortifications reaching from the South of France to the Northern parts of Norway. In some areas the defenses were quite formidable, whereas in others areas they were lacking. In this video I give you a short overview on the French parts of the Atlantic Wall and then show you how an individual infantry division was setup for coastal defense.

Principles and Organization of the Defense

Let’s start with the basic principles of the German defensive setup. The German High command analyzed the amphibious operations in Italy in 1943 and concluded that the most successful way to defend against an Invasion was to destroy the enemies landing force as soon as possible. The plan was to deploy strong forces in the coastal area in fortified positions, these troops should be stacked properly to provide a deep defense and supported by local reserves for counter-attacks. The units were ordered to hold out until the end. This should provide enough time to mount a strategic counter-attack with motorized units. (Deutsche Reich & 2. WK: Band 7; S. 463 (amazon.de affiliate link))

To give you some direct references, the German Army Command in the West (OB West) and it’s commander Generalfeldmarschall Rundstedt noted:
“Unser Vorfeldhindernis ist das Meer, der beste Panzergraben!” – “Our first defensive obstacle is the sea, the best tank ditch!” (Deutsche Reich & 2. WK: Band 7; S. 463)
And also “Im Bereich West gibt es kein Ausweichen.” (Deutsche Reich & 2. WK: Band 7; S. 463 (amazon.com affiliate link to the English Version))
“In the Area West there is no evasion.”

The last directive was probably influenced by the fact that the chances of surrendering were considerably higher on the Western Front than on the Eastern Front, because it was known to most German soldiers that they were treated quite well by the Western Allies. Thus surrendering was a viable option to German soldiers on the Western front. The German Generals were very well aware of this and it was quite troublesome for them. (Deutsche Reich & 2. WK: Band 7; S. 499-500) Since, we covered the basic principles of the defense, let’s take a look at the high-level organization of the defense.

Organization of the Defense on the strategic level

Among the German Commanders and leaders there was a consensus about the general defensive strategy, but there was some serious debate on how the units for a counter-attack should be deployed. There were basically two approaches, a decentralized approach in which motorized units were located closely to the front lines or a centralized approach, whereas a large group of units was stationed farther from the front. (Deutsche Reich & 2. WK: Band 7; S. 464)

In January 1944 a decisions was reached. One part of the tank divisions would be stationed close to the landing areas and additionally a central reserve would be deployed in Paris. The whole discussion and planning of the defense strategy was almost exclusively performed by army commanders, the Navy and Air Force were not really considered. (Deutsche Reich & 2. WK: Band 7; S. 464-465) So let’s take a look at the construction of the Atlantic Wall.

This is also reflected by the fact that the intention was to destroy the enemy during the invasion or shortly afterwards, but not prior to the landing, which was of course almost impossible due to Allied Air and Naval superiority. Yet, it underlines again the primacy of the German Army above the other branches. (Deutsche Reich & 2. WK: Band 7; S. 465)

Construction Process

The construction of the fortifications initially was mainly aimed at freeing up soldiers for the other front lines. Yet this changed in Fall 1943, up from that point more focus was put into providing a strong defense against an upcoming invasion.(Deutsche Reich & 2. WK: Band 7; S. 466)

The German High Command assumed an attack would be most likely in the Calais and Le Havre area, thus there was a strong regional focus on these areas. The regions of Normandy and Bretagne were of lesser importance, but everything else in France was of minor importance and very little fortifications were planned and constructed there. (Deutsche Reich & 2. WK: Band 7; S. 465)
The constructions of the Atlantic Wall required a large amount of construction workers. Although many foreign workers were transferred into Germany, in June 1944 still around 140 000 non-Germans and 18 000 Germans were used for the build-up of the Atlantic Wall. (Deutsche Reich & 2. WK: Band 7; S. 466) Yet, a large part of these workers were used to repair damages from the Allied bombing campaign and French Resistance attacks, furthermore some were also used for building up V-weapon bases. (Deutsche Reich & 2. WK: Band 7; S. 466) Let’s take a look at the total numbers.
Until the end of 1943 around 8500 fortifications and emplacements were constructed. Until the invasion about 12 200 (12247) fortifications in total were finished on the Western French Coast. Additionally, half a million beach obstacles and 6.5 million mines were placed. These fortifications were equipped with a large amount of artillery, anti-tank and anti-aircraft, which were often protected by concrete emplacements. In the Normandy region there was often a lack of resources and workers, thus even some large guns were without proper fortifications. Yet, in the areas were the Germans anticipated an Allied attack the fortifications were numerous and well-protected against bombing attacks. (Deutsche Reich & 2. WK: Band 7; S. 467-470)

Organization of the Units

Now, the chain of command and the authorities were quite complicated due to regional, functional and other structures. Some of these structures may have been useful, but often it was more about the prestige of some commanders. I spare you the details and just give you an example on how the various “relationships” of the 2nd Panzerdivision. (Deutsche Reich & 2. WK: Band 7; S. 474-475)

The division was part of the Panzergruppe West, operationally it was under the authority of the I. SS-Panzerkorps, territorially (05:00) it was under the command of the Military Administration in Belgium and Northern France and in terms of supplies it was attached to the 15h Army. This layout was not an isolated case. (Deutsche Reich & 2. WK: Band 7; S. 474-475)
CAPTION: „I will get a Bier now, because you are all drunk anyway.“
After all German bureaucracy is like war, and war never changes.

Overall Troop Quality

Let’s take at the quality of the troops. The units that manned the fortifications of the Atlantic Wall were mostly second rate German infantry divisions, they so called “bodenständige Divisionen”, which were infantry division intended for a static defense. They only had a very limited amount of transport capacity, no recon units and usually only 2 infantry regiments instead of 3. Furthermore, they often lacked properly trained NCOs and officers. These units were also often equipped with various captured equipment, thus of lower quality and complicating the logistical situation. (Deutsche Reich & 2. WK: Band 7; S. 481) In total around 25 of these static divisions were present since Fall 1943. (Deutsche Reich & 2. WK: Band 7; S. 476)
Additionally, various units were shipped to France to be regrouped and reinforced, yet usually these units were extremely depleted and exhausted. Thus, they were of limited use especially since the often replaced other troops that were transferred out to other front lines. (Deutsche Reich & 2. WK: Band 7; S. 476)

The motorized divisions, which should constitute a counter-attack were limited initially. In Fall 1943 only 2 were deployed in France, yet this number increased to 11 divisions until June 1944. About 5 of these units were sufficiently equipped, but the 6 others lacked tanks and other equipment. In total there were about 1860 armored vehicles available at the time of the invasion. (Deutsche Reich & 2. WK: Band 7; S. 480-481)

The State of the Air Force and Navy

Before we take a look at the defense layout of an infantry division on the coast, some information about the overall state of the German Air Force and Navy on the Western front. The situation was dire and got worse, it was unable to provide proper defense against the continuous air strikes from the Allies. Furthermore, in May 1944 the Allies focused their bombing attacks on the German fuel production, which considerably limited the ability of the Luftwaffe in its mobility and training. In case of an invasion, it was planned to transfer several air units from other areas. Yet, still that would only bring the number of planes to a total of around 1650 operational aircraft. (Deutsche Reich & 2. WK: Band 7; S. 483-485) At the same time the Allies had more than 9000 aircraft available over Normandy. (Source: Wikipedia )

This air supremacy of the Allies also prevented almost any operations of the German Navy. Due to detection by enemy radar the German ships couldn’t leave the harbors without being faced with immediate air and naval attacks. Thus, deploying naval mines in a systematic fashion was not possible. There were German plans to mine the coastal regions in Normandy, but the Allies successfully prevented these operations. (Deutsche Reich & 2. WK: Band 7; S. 485-487)

Defense Layout for of an infantry divisions (348th Infantry Division)

Now, lets take a closer look at the defense layout of the coastal region that was defended by the 348th infantry division. It was a bodenständige Division, thus intended for a static defense. The coastal area defended by this unit was about 30 to 35 km in length. On the Northern flank the 344th Infantry division and on the Southern flank the 245th infantry division were deployed.

Infantry Regiment Deployment

The 348th consisted of two infantry regiments. One regiment defended the Northern region and the other the Southern region.
There are numerous emplacements and defensive positions. I don’ really have any clear information about them, but I assume most of them were fortified with concrete fortifications considering the amount of passive defenses.

Artillery Deployment

The southern region contained a company from a coastal artillery battalion or “Heeres-Küsten-Artillerie-Abteilung” and an army artillery battalion or “Heeres Artillerie-Abteilung”. As far as I know these battalions were not part of the division itself, which had its own artillery regiment. A total of 14 batteries of these units were deployed at the following positions. And furthermore, there were another three batteries for 10cm artillery pieces.

Passive defenses, mines and obstacles

Now there were various static defense and obstacles:
First off there were a “few” mine fields, yeah, well, now you know why they needed 6.5 million of those little bastards.
There were 4 areas that were protected by hedgehogs in front of them.
Another 5 areas that used ramming logs some of them are located in the water or directly on the beach area.
And finally one area was protected by an anti-tank wall, which was the location of one the headquarters units. So let’s take a closer look at those.

Headquarter units

The headquarters unit for one infantry regiment was located here at the anti-tank wall, which is located right behind the forward area of the defenses and also in well centered. The same goes for the second regiment headquarters in the South. At little bit more behind, but again in the center is the divisional headquarters located, which is also the position for the headquarters of the artillery regiment and the signal battalion.

Reserve Areas

Now there were 5 areas for reserves, 4 of divisional reserves and one regimental reserve. The only regimental reserve was located very close to the front line in the North. A little bit more behind was a divisional reserve area. Then there was a large reserve area next to the division headquarters, where a company of assault guns and an anti-tank platoon were deployed. There was another reserve area next to the division HQ and one in the Southern area close to the front line.

Conclusion

To summarize, the Atlantic Wall wasn’t an impenetrable defensive line nor was it just hollow propaganda. The quality and quantity of the defensive positions varied a lot and was closely related to the German Commanders assumed invasion location, which was not the Normandy. The strategic reserve to counter an invasion was deployed as a decentralized reaction force in combination with a centralized mobile force to perform counter-attacks.

Due to the Allied Air Superiority the German Air Force and Navy were basically incapable of providing any substantial contribution during the preparation against the invasion and the invasion itself. Furthermore, the constant air strikes severely reduced the amount of the available work force due to the need for repairs that couldn’t be spent on constructing fortifications and obstacles.

Sources

Books

Das Deutsche Reich und der Zweite Weltkrieg – Band 7: Das Deutsche Reich in der Defensive – Strategischer Luftkrieg in Europa, Krieg im Westen und in Ostasien 1943-1944/45 (amazon.de affiliate link)

Germany and the Second World War – Volume 7: The Strategic Air War in Europe and the War in the West and East Asia 1943–1944/5 (amazon.com affiliate link)

Fortress Europe: Hitler’s Atlantic Wall by George Forty (amazon.com affiliate link)

amazon.com amazon.co.uk amazon.ca amazon.de

Disclaimer amazon.com

Bernhard Kast is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

Disclaimer amazon.co.uk

Bernhard Kast is a participant in the Amazon EU Associates Programme, an affiliate advertising programme designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.co.uk.

Disclaimer amazon.ca

Bernhard Kast is a participant in the Amazon.com.ca, Inc. Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.ca.

Disclaimer amazon.de

Bernhard Kast ist Teilnehmer des Partnerprogramms von Amazon Europe S.à.r.l. und Partner des Werbeprogramms, das zur Bereitstellung eines Mediums für Websites konzipiert wurde, mittels dessen durch die Platzierung von Werbeanzeigen und Links zu amazon.de Werbekostenerstattung verdient werden können.

Online Resources

Heeres-Küsten-Artillerie
Heeres-Artillerie-Abteilungen
348th Infantry Division