Japanese roadblocks were a thing. During their initial invasion of Burma, Japanese strategy often involved infiltrating whole regiments behind enemy lines then installing roadblocks to cut off the retreating Allies. So I went looking for some source material. I found a couple of interesting war time articles by the Americans on Japanese roadblocks and some more about roadblocks in Burma. I’ll discuss why the Japanese were keen on roadblocks, the nature of the roadblocks themselves, the terrain selected for a roadblock, and typical defenders.
Why roadblocks
A couple of overturned trucks doesn’t sound much but the Japanese infiltration and roadblock strategy was very effective and almost, almost, completely destroyed the Burma Corps in Burma in 1942. The strategy involved infantry regiments infiltrating behind the Allied lines, putting in roadblocks, thus cutting off the Allies, and hopefully destroying them. The strategy was very effective and although the British and Chinese managed to retreat out of Burma, it was a near run thing, and they took a hammering in the process. Roadblocks were key to the strategy. Roads were few and a well placed series of roadblocks could hold up the retreating allies for days.
In the Malaya and Burma campaigns, the Japanese frequently used road blocks to great advantage. Their success was largely due to these factors: the jungle or swampy nature of the terrain, the scarcity of roads, the necessity of the British using the few roads available because their forces were largely motorized, and the fact that the Japanese usually outnumbered their opponents.
War Department (1944, p. 125):
b. Road blocks. Due to the paucity of roads, road blocks are especially effective in slowing up the movement of road-bound equipment.
…
The Japanese have established road blocks in rear of the enemy, along his route of withdrawal. An enveloping force or raiding party is generally charged with this mission, which is very effective in disrupting the movements of the enemy at a critical time.
The Taukkyan roadblock was so effective that the British were considering splitting up the army into groups of 12 men and telling them to make their own way to India (Latimer, 2004, p. 70-71):
the situation looked grim as Alexander made a plan for an all-out attack the following morning. If this plan failed, the alternative was even more desperate: the army was to split into parties of twelve and ‘make their way to India independently’.
Nature of roadblocks
Most Japanese roadblocks were not flash being improvised out of whatever was available: tar barrels, felled trees and captured lorries. Having said that, if the Japanese had time they would construct something more solid.
The 7th Armoured Brigade – Engagements – 1942 describes roadblocks made up of tar barrels, felled trees and overturned captured lorries. Although the list was for a particular stretch of road, it seems to apply generally.
As the British and Indian formations would travelled along the road to Prome the 40-mile long convoy of 1,400 British and Indian vehicles were held up from time to time by roadblocks made up of tar barrels, felled trees and overturned captured lorries defended by field guns on both sides. Only determined ‘hook’ attacks around the flanks were likely to succeed.
the road block which consisted of two lorries drawn across the road and another obstruction some 300 yards farther down the road. … The lorries were easily moved by the tanks.
The blocks, as a general rule, were hastily prepared and were not very strong. Most of them could be broken easily by a powerful frontal assault, led or supported by tanks. Breaking through one barricade, however, was usually not enough, because the Japanese used them in series–at Shwedaung, Burma, five barricades had to be broken on one road before the British could continue their march. The Japanese also made a practice of closing in on the roads behind the British, thus blocking them off from units farther back.
The Japanese often used layers of roadblocks, so if the Allies broke through one, they would just find another. 1942-03-29 Shwedaung Map
All Japanese infantry divisions had mines available and in exercises all units would lay mines (War Department, 1944). So, if they had time, the Japanese mined alternatives routes and temporary roadblocks as a extra surprise for the attackers (p. 117):
Tank barricades have all possible detours heavily mined, and it is common practice to lay a few mines under temporary barricades with the idea that if the enemy removes the barricade, he will not suspect that mines have been laid in the ground underneath.
Terrain near roadblocks
The Japanese didn’t need strong roadblocks because they were experts at placing them. The ideal location was a road through difficult terrain – woods, rice paddies or swamps – with the roadblock itself being concealed. Woods/jungle, for example, provided concealment for both the roadblock itself and the ambushers. The killing zone was created by placing the roadblock out of sight around a bend in the road, with the concealed guns aimed at the bend. The approaching enemy only knew they had a problem when they were already in the killing zone.
The siting of the Jap road blocks was invariably good. They were located at points where the road passed through dense jungle or other enclosed country, such as rice fields or swamps. The actual blocks or barricades were always concealed from frontal observation except at a very short distance. They were strongly covered by well-sited mortars, light machine guns, and antitank guns. These weapons were placed in defiles–behind ridges or in hastily constructed holes or trenches. The frontage held on each side of the road was comparatively short, partly owing to the nature of the country.
War Department (1944, p. 75) elaborates on the “jungle”
5. AMBUSHES AND ROAD BLOCKS. a. Ambushes. The jungle offers many ideal opportunities for ambush which the Japanese have exploited, and they have been trained well in this type of operation. The size, composition, and armament of the force depend on the mission. No new principles are involved.
b. Road blocks. Due to the paucity of roads, road blocks are especially effective in slowing up the movement of road-bound equipment. One method is to place a block across the road, just around a bend. The party defending the block is disposed on either side of the road, and an antitank gun, or a larger caliber weapon is located in prolongation of the road, before the bend. These weapons are emplaced close to the block and are fired at point blank range. (See fig. 100.)
Latimer (2004, p. 70-71) described the woods on each side of the road at the roadblock at Taukkyan, Burma:
The villages either side of the road were practically all enclosed in woods and while these woods and villages entailed jungle fighting, noted Lieutenant-Colonel Charles Bagot commanding 1st Glosters, ‘there was no jungle in Burma during the course of the campaign, which was comparable to some found in Assam … or parts of Malaya. The snake-infested impenetrable jungles so freely talked about in connection with this Campaign were a myth.’
The roadblock was always concealed around a bend. The roadblock south of Pegu had both both elements of the Japanese preferred terrain: the bend in the road and in woods ( The 7th Armoured Brigade – Engagements – 1942):
On coming round a bend it suddenly came up against the road block which consisted of two lorries drawn across the road and another obstruction some 300 yards farther down the road. The country on either side was heavily wooded and there was no way round. The lorries were easily moved by the tanks, but immediately came under a hail of small-arms fire.
Defenders
The Japanese infiltrated infantry regiments with integral guns, both anti-tank and howitzers.
War Department (1944, p. 125)
The size, composition, and armament of the force depend on the mission. No new principles are involved.
…
The party defending the block is disposed on either side of the road, and an antitank gun, or a larger caliber weapon is located in prolongation of the road, before the bend. These weapons are emplaced close to the block and are fired at point blank range. (See fig. 100.)
The Japanese have established road blocks in rear of the enemy, along his route of withdrawal. An enveloping force or raiding party is generally charged with this mission, which is very effective in disrupting the movements of the enemy at a critical time.
The Americans also interviewed a British officer about Japanese roadblocks (The U.S. War Department (1942, September) quoted in Lone Sentry: Japanese Tactics in Burma):
The following information is based on a report by a British officer of the fighting in Burma. As will be readily seen it is not a complete analysis, but simply a collection of miscellaneous notes.
Tactically the Japanese relied for the most part on the ambush. The ambushes were generally very skilfully located, but were always on the same pattern, particularly with reference to the positions of weapons.
The chief form of enemy defense encountered was a combination roadblock and ambush. The position was invariably located at a point where woods converged on the road. Covering weapons were effectively located. Light machine guns in dispersed positions were placed forward of the woods, and snipers spotted in the woods to prevent envelopment of the position. The roadblock is also covered by one or more heavy weapons. In three instances a French 75 (probably taken in Indo-China) was encountered at a roadblock. In each instance the block was in a bend of the road, and the gun was placed in a concealed position off the road about 50 yards beyond the block on a line in prolongation of the original direction of the road. To knock out this gun the area may be searched with artillery and mortar fire, but its elimination is primarily an infantry task to be accomplished by mopping up the gun crew with small arms. In addition, a 37-mm antitank gun may be placed very close to the roadblock, usually on the opposite side of the road to the 75-mm gun; a 4-inch mortar may be emplaced further to the rear.
Handbook Figure 100. Japanese road block.
The Japanese 37-mm antitank gun is only 2 feet high, being supported on small wheels. It is thus easily concealed and is usually put in position in a ditch or in the shadow of a building. It may also be found near culverts which the crews use when being shelled.
The Japanese 4-inch mortar is not as highly effective as some reports would indicate. For effect it depends entirely upon blast and its killing power is very limited. One of its chief dangers is its incendiary powers against halted vehicles. When attacked by British mortar fire, the fire of this weapon became inaccurate. If the counter-mortar fire was at all accurate the enemy moved the gun. As soon as its position has been determined, it should be overrun by infantry. When the 4-inch mortar is used in support of road blocks it is generally emplaced near the road, but farther to the rear than the 75-mm and antitank guns.
The Japanese have invariably emplaced their light machine guns a short distance in front of the forward edge of a woods. This is done in order to escape artillery or mortar fire which may be directed at the edge of the woods. The machine guns are not dug in, but they are cleverly concealed by use of background; every precaution is taken to eliminate splash. The guns are normally fired on fixed lines along the edge of the woods. In attacking the machine guns, artillery and mortar fire should start some 50 yards in front of the edge of the woods, and the leading infantry must follow the barrage as closely as possible. Any formation in line, or bunching, by the attacking infantry is suicidal. From the jump-off point until the objective is overrun the infantry must remain widely dispersed; within platoons at least one section should be held in reserve, and sections should maintain a patrol formation.
In wood and jungle fighting the Japanese snipers presented a most difficult problem. They remained at their posts with great bravery, and in the opinion of the reporting officer they had been assigned a definite time to remain there. Snipers took positions in trees, on the ground, and in houses. The elimination of snipers in trees or on the ground is the task of the individual soldier. Care must be taken not to advance in a straight line; one should get behind a tree, observe in all directions, both on the ground and up in the tree, and then move very rapidly to a tree about 10 yards to the right or left front. This process is repeated, and it is probable that the sniper will either be spotted or that the stalker will get behind him, and have the sniper at his mercy. Snipers posted in houses present a different problem, and experience shows that too many casualties occur if stalking is attempted. The best means of attack appears to be either to burn them out or use grenades under the protection of smoke.
The Japanese were very adept in the use of camouflage and altered their appearance according to the nature of the terrain that they were traversing. Examples of their use of camouflage were these: a green net for the helmet, long green gloves, bottle-green liquid carried to color face and rifle, different colored shirts carried by the individual soldier, and elephants colored with varying shades of green paint.
Roadblocks made up of tar barrels, felled trees and overturned captured lorries defended by field guns on both sides. Only determined ‘hook’ attacks around the flanks were likely to succeed.
The siting of the Jap road blocks was invariably good. They were located at points where the road passed through dense jungle or other enclosed country, such as rice fields or swamps. The actual blocks or barricades were always concealed from frontal observation except at a very short distance. They were strongly covered by well-sited mortars, light machine guns, and antitank guns. These weapons were placed in defiles–behind ridges or in hastily constructed holes or trenches. The frontage held on each side of the road was comparatively short, partly owing to the nature of the country.
On occasion the Japanese fielded their own tanks, in this case Type 95s, as 7th Hussars discovered near Pegu (Latimer, 2004, p. 68):
Seventh Hussars, which had relieved 2nd Royal Tanks, were ambushed south of Pegu by Japanese 37mm anti-tank guns, in turn counter-attacked by the supporting 1st West Yorkshire Regiment company and overrun, killing most of the gunners. Soon afterwards the Hussars encountered three Japanese tanks, brought with difficulty from Thailand, and knocked them out.
1942 – Burma – Japanese Road Block – Position of weapons
How to attack Japanese roadblocks
The typical British approach to the roadblocks was an artillery barrage preceding a frontal assault, with any tanks in front, and infantry advancing in waves. To clear the road the British realised it was necessary to control both sides. I suspect British tactics were naive at this time of the war, relying on poorly trained troops. Later on they could go for more nuance and lower casualties.
Because of the jungle nature of the area on both sides of the road, only strong frontal attacks on a comparatively narrow front should be attempted. The attack must be carefully prepared and supported by every ounce of firepower available. It should be supported by barrage fire from all available artillery and mortars. Some of these weapons should be available for searching fire against enemy mortars in case the latter are used. The infantry should attack in waves with strictly limited objectives, each wave halting on its objective and taking up an all-around defensive position to be held until the whole column has passed. If tanks are available, they should precede each successive leading wave of infantry at infantry pace. Each leading wave of infantry must, in its turn, employ shock tactics, combining grenades with the fire of submachine guns, machine carbines, and Bren guns, and with the use of bayonets. It is necessary to capture and hold both sides of the road throughout the area so that the enemy cannot return to his positions dominating the route. But because of the jungle terrain, it is not necessary to hold a wide area on both sides of the road–strips wide enough to keep the enemy from observing the road are sufficient.
Only determined ‘hook’ attacks around the flanks were likely to succeed.
I have a sneaking suspicion the British tendency for frontal assault was because of the poor quality of the troops. In 1942 the Anglo-Indians were not trained to fight in the jungle. In fact some units, when sent to attack an roadblock in woods, often got dispersed with few troops actually reaching the destination. I think this happened at Taukkyan but I can’t find the reference just at the moment. Of course things would change as the war progressed and the Anglo-Indians focussed on jungle warfare.
On occasion the British attacked roadblocks from both directions. For example Field Marshal Viscount Slim has this to say about Sittang mentions this at Shwedaung (Slim, 2009):
Anstice’s advance guard attacked a roadblock at the souther end of the town, while the two battalion attacked the norther outskirts.
War Department. (1944, 15 September). Technical Manual Handbook on Japanese Military Forces. United States Government Printing Office. [Available on-line https://www.ibiblio.org/hyperwar/Japan/IJA/HB/HB-7.html.]
Most interesting. I am not well read on the Burma theater. I have read SLA Marshall’s work on an early Korean War battle, The River and the Gauntlet. McArthur ordered an attack towards the Yalu, discounting the possibility of Chinese intervention. After several nights of Chinese attacks, the UN forces had to withdraw. Chinese troops had infiltrated in large numbers through low ground, following watercourses, while UN forces defended high ground. When the 2nd Division withdrew, it had to go 10 miles down a road that was flanked on both sides by some 10,000 enemy troops. They didn’t build any roadblocks, but the retreat was harrowing and costly. Some units, like the anti-aircraft with quad 50s on halftracks, made the trip fairly easily. Some rear area units were overrun by infantry attacks on the road. It was a bloody 10 miles down to where the Commonwealth brigade was waiting for the survivors.
Most interesting. I am not well read on the Burma theater. I have read SLA Marshall’s work on an early Korean War battle, The River and the Gauntlet. McArthur ordered an attack towards the Yalu, discounting the possibility of Chinese intervention. After several nights of Chinese attacks, the UN forces had to withdraw. Chinese troops had infiltrated in large numbers through low ground, following watercourses, while UN forces defended high ground. When the 2nd Division withdrew, it had to go 10 miles down a road that was flanked on both sides by some 10,000 enemy troops. They didn’t build any roadblocks, but the retreat was harrowing and costly. Some units, like the anti-aircraft with quad 50s on halftracks, made the trip fairly easily. Some rear area units were overrun by infantry attacks on the road. It was a bloody 10 miles down to where the Commonwealth brigade was waiting for the survivors.
that does sound pretty tough.
Very interesting. I guess we will have soon some dramatical scenarios.
I will play it in Malaya where the japs often used roadblocks ( even bypassing commonwealth units by sea then going to their rear)
Yup. We played a game this week as a bit of experiment, which I’ll post about soon.
Interesting article Steven.