A Study in Armored Exploitation The Battle of the Slim River: Malaya, 7 January 1942

reserves to counterattack them when they appeared. This would keep their forces mobile along the road system. The 12th Brigade took up forward positions with its battalions arrayed in depth, beginning in the vicinity of mile post 60 and extending back to mile post 64 (see map, following page). Two battalions of the Indian Army occupied the forward positions; the 4/19th Hyderabad occupied the initial outpost position and the 5/2nd Punjabi occupied the main defense about a mile back. A third British battalion, the Argyl and Sutherland Highlanders, was positioned in the vicinity of Trolak village, where the jungle began to open out onto an estate road. The brigade reserve, the 5/14th Punjabis, was positioned at Kampong Slim with the mission of being prepared to move to a blocking position one mile south of Trolak near mile post 65. The 28th Brigade’s positions were south of the 12th along the maneuver corridor, and were arrayed as single battalions in depth, much like the 12th Brigade. However, on the early morning of January 7th, the brigade had still not occupied the positions, having been instructed by General Paris to rest and reorganize.2 The British infantry units had 12.7-mm antitank rifles and 40-mm antitank guns. The AT rifles were only marginally effective. The AT guns would penetrate any Japanese tank with ease. A key to the defensive scheme would be the defenses and obstacles along the main road. The British should have had enough time to construct defenses that would have precluded a quick Japanese breakthrough. The British were also in the process of preparing to demolish numerous bridges along the main road. However, several factors were to conspire against them.

The first factor was fatigue. Their forces were tired, to the point where they didn’t do a good terrain analysis when setting in their defense. There were many sections of the old highway running parallel to the newer sections that had been straightened. These old sections ran beside the main road through the jungle and were excellent avenues of approach. There were also numerous side roads through the rubber plantations, and many of these roads were overlooked. Others were noted, but did not have sufficient forces allocated to them.

Secondly, the British units had all suffered numerous casualties. Many of their formations were under new and more junior leadership. These leaders were trying to cope with the monumental task of reorganizing their stricken units while conducting defensive preparations, and they were suffering from fatigue as much as (if not more so) than their troops.

Another critical British deficiency was communications equipment. The 11th Indian Division had lost a great deal of its signal equipment in the month-long retreat prior to the Slim River battle. As a result, there was not sufficient communications equipment to lay commo wire between the brigades. This lack of communications, combined with fatigue, also prevented the British artillery from laying in and registering its batteries to support the infantry positions. Lastly, the Japanese had complete mastery of the air. This precluded the British from moving up their supplies in daylight and severely limited the extent of their defensive preparation.

All of these factors combined to rob the British of their opportunity to build a cohesive defense. They had sufficient barrier material, in the form of mines, concrete blocks, and barbed wire to construct an effective obstacle system in depth, but at the time of the Japanese attack, only a fraction of it had been brought forward. In the location where the Japanese actually broke through, there were only 40 AT mines and a few concrete blocks emplaced when the Japanese attacked.3 On the afternoon of the 5th, the British 5/16th (the covering force) withdrew, and soon afterward the advance guard of the Japanese 42nd Regiment, 5th Infantry Division, made contact with the forward elements of the Hyderabad battalion. The Japanese probed the Hyderabads’ forward positions and were repulsed. The Japanese advanced guard commander, Colonel Ando, decided to wait for tanks and other supporting troops. The 6th of January was spent by the Japanese reconnoitering the British defenses and preparing for their usual infiltration along the British flanks.

Major Shimada, the commander of the Japanese tank unit attached to the 42nd Infantry (a company plus of 17 medium and 3 light tanks from the organic tank battalion of the Japanese 5th Infantry Division) implored Colonel Ando to be allowed to attack straight down the road. Ando was at first skeptical, but finally acquiesced, reasoning that if the tank attack failed, the infiltration could still continue.4 The Japanese tank company, with an attached infantry company and engineer platoon in trucks, was set to begin the assault at 0330 the next morning.

The Japanese attack began with artillery and mortar concentrations falling on the 4/19th Hyderabad’s forward positions, while at the same time infantry units assaulted the forward positions of the Hyderabads, and engineers cleared the first antitank obstacles along the road. At approximately 0400, the Japanese armored column started forward, crewmembers initially ground-guiding their vehicles through the British obstacle.

The Hyderabads had no antitank guns, but did manage to call artillery fire on the Japanese, which knocked out one tank. The rest of the Japanese column swept through the breach and continued down the road to the next battalion position. Behind them, the remainder of the 3rd Battalion, 42nd Infantry, completed the destruction of the Hyderabad battalion, leaving only disorganized and bypassed elements to be mopped up later.

The Japanese column moved on. By 0430, it had reached the main defensive belt of the 5/2nd Punjabi battalion. The lead tank hit a mine and was disabled, and the remainder of the column stacked up behind the disabled vehicle almost bumper to bumper. The Punjabis attempted to knock out the Japanese tanks with Molotov cocktails and 12.7-mm antitank rifles, but were largely stopped by a heavy volume of fire from the Japanese tanks and infantry. At this point, the Japanese found one of the unguarded loop roads that paralleled the main road and took it, bypassing the Punjabi defenses and taking them in the flank. The Punjabis’ defense collapsed into a series of small units fighting where they stood or trying to escape. The Japanese armor continued on, leaving the tireless 3d Battalion, 42nd Infantry, and other elements of the Japanese advance guard to complete the destruction of the Punjabis.

Unfortunately for the British, this was the last prepared defensive position facing the Japanese. The Punjabis had emplaced only a single small minefield. In spite of this, they somehow managed to hold the Japanese for almost an hour, taking heavy casualties from the tanks’ fire, before the Japanese found another loop road and were off again. It was about 0600; the Japanese were exploiting like broken-field runners. Almost 1,000 British and Indian soldiers were dead, prisoners or fugitives in small groups heading south along the edge of the jungle. Tragically for the British, no word of the fiasco had reached either the remaining battalions of the 12th Brigade (the Argyls and the 5/14th Punjabis) or the 28th Brigade. The Japanese armored juggernaut, (about 16 tanks strong at this point), with what remained of the accompanying infantry and engineers, continued south at a fast pace.

The next unit they encountered was the unsuspecting Argyl and Sutherland Highlanders, who had established two roadblocks in their defensive sector. The speed of Japanese movement, and the abysmal nature of British communications, caught the Argyls unaware and unprepared. The Japanese column burst through the first blocking position almost before the Argyls could offer any resistance. The fight at the second roadblock took only a little longer, with the Japanese destroying several British armored cars before continuing on. The remainder of the Argyl battalion was engulfed by the follow-on Japanese infantry in much the same manner as the other battalions.

To their credit, the Argyls fought ferociously in small groups and held the Japanese infantry longer than any of the other battalions. This, in turn, increased the distance between the Japanese armored column and the follow-on infantry. Had the 28th Brigade been in a better defensive posture, this might have made a difference. As it was, the Argyls’ sacrifice was in vain. The Japanese tankers took full advantage of the confusion in the British defense to continue their advance down the main road towards the Slim River bridge. Upon reaching Trolak, they scattered the engineers who were preparing the bridge for demolition. The lead tank platoon leader, Lieutenant Watanabe, personally dismounted from his command tank and slashed the demolition electrical wires with his sword.5 The lieutenant and his company commander sensed that they had the momentum in this drive and that it was urgent to keep the pressure on the disorganized British. The Japanese tanks and the few remaining infantry and engineers that had somehow stayed with them raced ahead. It was approximately 0730. South of Trolak, the Japanese armor encountered the 5/14th Punjabis, who were moving along the road in march column towards their designated blocking position. The tanks literally raced through the surprised battalion, machine-gunning a large number of the Punjabis before they could even get off the road. In only a few minutes, the 12th Brigade’s reserve ceased to exist as an effective unit. The Japanese armor continued its unchecked advance along the main road. The British had lost track of the battle. General Paris was not informed of the breakthrough until 0630.6 He immediately ordered the 28th Brigade to occupy its defensive positions and to detach its antitank battery forward to the 12th Brigade. Unfortunately, the battery met the Japanese while moving up the road and was destroyed before it could unlimber its guns and engage the enemy. Thus, one of the few units in the 28th Brigade that was capable of stopping the Japanese armor was eliminated at the outset of that brigade’s fight. Incredibly, the 28th Brigade had not received word of the complete penetration of the 12th Brigade. The Japanese armor slammed into the 28th Brigade while it was moving to its defensive positions and swept it aside in a series of short bloody encounters. Like the 5/14th Punjabis, the 2/1st Gurkhas were surprised in march column on the road while moving to their defensive positions and suffered severe casualties before they could get out of the way of the Japanese armor. The other battalions of the 28th Brigade, 2/9th and 2/2nd Ghurkas, tried to engage the Japanese armor, but with no antitank obstacles and only a few 12.7-mm AT rifles, they were quickly bypassed. The Japanese armor continued to move down the road, shooting up transport columns and disrupting demolition efforts on the road and at three lesser bridges. The Japanese tanks had by now completely outrun their accompanying infantry and engineers. The follow-on infantry battalions continued to fight through the disorganized defenses bypassed by the armor. The Japanese tanks next shot up two artillery batteries of the 137th Field Regiment before reaching the Slim River bridge at approximately 0830. The antiaircraft defenses of the bridge consisted of 40-mm Bofors antiaircraft guns. These engaged the Japanese tanks but were ineffective — their shells would not penetrate. Their crews took many casualties from Japanese return fire. The antiaircraft gunners and the engineers preparing demolitions on the Slim River bridge scattered. Lieutenant Watanabe (who was wounded by this time) directed the machine gun fire of his tank against the wires to the bridge demolition and succeeded in severing them. The Japanese force (by this time consisting of about a dozen tanks) left two of their number to guard the bridge and continued south along the main road. Finally, after continuing for two more miles, the Japanese ran into another British artillery battalion, the 155th Field Regiment. This artillery unit deployed its 4.5-inch howitzers in the direct fire mode and engaged the Japanese over open sights at less than 200 meters. The lead Japanese tank (commanded by Lieutenant Watanabe) was destroyed and the entire crew killed. Other Japanese tanks were damaged. Checked at last, the Japanese tankers returned to the Slim River bridge to guard their valuable prize. The Japanese infantry accompanying the tanks, not less than a company in strength, arrived a few hours later. The main body of the 42nd Infantry Regiment did not link up with the armored unit until almost midnight. The Japanese had lost about eight tanks, some of which were recoverable. Their infantry losses had been moderate, but re-placable. Their morale was sky high.

Summary

The Japanese had won a smashing victory. In the space of about seven hours, with a single company of obsolete tanks supported by infantry and engineers, and followed by an infantry regiment (-), they had almost completely destroyed an entire British division. By the afternoon of the 7th of January, the British units the Japanese armor had bypassed were a jumble of disorganized fugitives. In the best shape were the infantry battalions of the 28th Brigade, who could retreat across an adjacent railroad bridge. In the worst shape were the men of the 12th Brigade; literally all of them were either killed, taken prisoner, or moving in fugitive groups trying to infiltrate back.

The losses to the Argyl and Sutherland Highlanders were especially tragic to the British, as they had repeatedly proven themselves to be the best trained battalion in Malaya. Had they not been surprised by the Japanese armor, they could conceivably have held the Japanese advance long enough for the 28th Brigade to have reached its positions and unlimbered its antitank guns. The battle probably could not have been salvaged, but at least a more orderly retreat would have been possible, followed by the demolition of the Slim River bridge. As it was, less than one hundred men of this battalion managed to reach British lines. The magnitude of the disaster is reflected in the number of survivors from each brigade. Only 400 men of the four battalions in 12th Brigade managed to break out and rejoin the retreating British army. The 28th Brigade did slightly better, with approximately 700 men, but this unit was also clearly decimated. All in all, the British lost two brigades in the Slim River battle, along with most of two battalions of artillery, as well as transportation, signal, engineer, and other supporting units. Those British and Indian soldiers and units that escaped, escaped on foot. Not a single vehicle was retrieved from north of the Slim River.

The remainder of the Japanese pursuit of the British down the Malay peninsula retained the same flavor as the Slim River actions — relentless, aggressive Japanese pursuit of tired British units who had suffered too many losses in personnel and equipment and who could never keep the Japanese from operating inside their decision cycle. The Japanese did meet a series of reverses when they encountered fresh Australian troops of the 8th Australian Infantry Division. A cautionary note on headlong armored exploitation was sounded just 11 days later near the small town of Bakri. The Japanese attempted to repeat their Slim River success by sending alight tank company to attack down the main road. The Australians defending the antitank obstacle on the road coolly waited for the Japanese to begin negotiating the obstacles and then quickly knocked out nine Japanese tanks with antitank gun fire. The accompanying infantry was also temporarily stopped by the Australians, suffering numerous casualties.

The Japanese formula from Slim River was unchanged. The defenders however, were fresh troops who had had the opportunity to emplace their defense properly. Unfortunately for the Australians, the rest of the British forces were simply too depleted from their earlier defeats to offer an effective resistance. As a result, they were compelled to retreat to the island of Singapore with the rest of the British army, abandoning Malaya to the Japanese on 30 January. Singapore would surrender two weeks later. Lessons Learned

• Armored exploitation and exploitation in general is something to be seized upon. Had the Japanese halted to regroup, or waited for additional forces after having penetrated the 12th Brigade near Trolak, the 28th Brigade would have had enough time to go into a hasty defense. The experience of the Japanese tank company that was shot up by the Australians while trying to repeat the events of January 7th shows what would have happened to the Japanese on that day had the British been able to get their antitank guns into action. The Japanese decision to press on was taken by junior officers and supported by their commander, who didn’t wait for a perfect sitrep. The Japanese knew that they had the British disorganized, and that they had to just keep hitting them.

• Like the OPFOR at the JRTC, the Japanese were able to avoid British defenses and sustain their momentum by pushing their mass down side trails that were poorly defended or undefended. They sacrificed frontage to do this, and on several occasions had amass of vehicles stacked up in column while only the first few in line could fight. Had the British been able to accurately mass artillery on them, they could have slowed their advance. However, the British often didn’t know the Japanese armor was there until it burst upon them out of the side roads. The momentum of the Japanese advance did not allow the British to track the battle effectively. The lesson here is that armor units cannot be wedded to wide avenues of approach. By assuming risk on the side roads, the Japanese were able to bypass British defenses and surprise the British units.

Japanese Armor at Slim River The Japanese used two types of tanks at the Slim River battle. The main medium tank used was the Type 94, which was the most common Japanese medium tank throughout the early part of the Pacific war. The light tanks used were Type 95s, which were encountered by Allied forces throughout the entire war. The Type 94 was an older design that was first introduced in 1934. Weighing 15 tons, its armor was only 17mm at its thickest. The tank had an advertised maximum speed of 28 mph, although 20 mph or less was the norm due to its being relatively underpowered. The 57-mm gun was a good infantry support weapon; however, there was no coaxial machine gun — the turret machine gun faced out of the turret rear. In addition, there was a hull machine gun. The Type 94 did carry a large amount of ammunition: 100 57-mm rounds and 2,800 rounds of machine gun ammunition. It was cramped for its crew of five men, and visibility from it was poor. There was no radio to communicate with other vehicles, communication being done by flags or shouted orders. The Type 94 had an unrefueled range of 100 miles. (See illustration on pp. 26-27.) The Type 95 light tank was a slightly newer design that had some of the same problems of the Type 94 as well as many of its own. The 10-ton tank had even thinner armor than the Type 94 (14mm). It was slightly faster than the Type 94 and could achieve its maximum speed of 25(+) mph. It was armed with a 37-mm gun, as well as two machine guns in a similar arrangement to the Type 94. However, the three-man crew could not operate all the weapons at once. The commander was particularly overtaxed, having to load and fire the main gun or turret machine gun, as well as command the tank. The Type 95 also had an operational radius of about 100 miles.

Source: Defeat In Malaya: Arthur Swinson, pp. 70, 71.

• Hand-in-hand with this is the lesson that “tankable terrain” is any place a tank can physically go. The British had dismissed Malaya as terrain unsuited for armored operations.7 The narrow frontages confronting them made even the limited number of Japanese tanks available decisive. In a narrow maneuver corridor, an armored unit does not have to be of divisional strength to have a critical impact on the outcome of the battle.

• The Japanese exploited their success by rushing units after their armored column as quickly as possible. Had they not done so, the armor, with its small complement of accompanying infantry and engineers, would have been overwhelmed and destroyed by regrouping British units. By following hot on the heels of the armor, the Japanese denied the British the opportunity to regroup.

• The Japanese proved again the value of a large volume of suppressive fire. Several times, the Japanese column was stacked up amongst the British defenses. The extremely high volume of fire placed on the British by the tanks and their accompanying infantry allowed them to survive this exposure until the obstacles could be reduced or a bypass found.

• The experience of the British in being unable to set in an adequate hasty defense is a stark example of the strain of retrograde operations under pressure. The unpreparedness of the British defenses was due largely to fatigue and the requirements of reconsolidation after a month of continuous fighting. There were sufficient mines and barrier materials, as well as antitank weapons and artillery, available for the British defensive scheme of maneuver. Anyone who shrugs off the British in this case study as just another unit that failed their defensive prep phase at the NTC is missing the point. What confronted the leaders up and down the chain of command in those two brigades was about as bad as it gets. They were planning a hasty defense in unfamiliar terrain while reorganizing units that were at about 66 percent strength from combat losses (a high percentage of those losses were leadership personnel). They hadn’t slept for two days, and were under constant air attack. Leaders at all levels should contemplate that, and think about how they’d overcome those conditions.

• A final lesson is an oft-repeated one in armored warfare. Ultimately, it isn’t the machines; it’s the men who drive them. The Japanese tanks were obsolescent, even by the standards of the day. The mediums could barely travel 18 mph and had very thin armor that could be penetrated with ease by British antitank guns. The light tanks were literally three-man tin cans, with the commander also acting as the loader and the gunner. The Japanese tank machine guns were magazine-fed, as opposed to belt-fed, and the visibility from the vehicles was poor. All in all, they were not ideal weapons of war. However, they were driven by crews who were well trained in their use, understood their capabilities, and who possessed a ferocious will to combat the enemy. This factor bears consideration in today’s world. When was the last time one of us shrugged off an enemy armed with T55s?

Although not involving nearly as many tanks as the great battles in Europe and Africa, the Japanese attack and exploitation at the Slim River was one of the most decisive uses of armor in WWII. Lieutenant Watanabe and Major Shimada and their men certainly belong in the ranks of the great tankers of WWII. Their exploit was equal to the best of the Americans of the 4th Armored Division, Rybalko’s Tank Guards, or Hermann Balck’s 11th Panzers. Although the vehicles they used were little better than tin cans, their offensive spirit and willingness to relentlessly pursue an off-balance enemy was in the best traditions of the combat arm of decision.