We’ve written about the primary ammunition for tank cannons, HEAT rounds and Sabot’s. But there was a brief period where it looked like squash would be the big tank killer.

The “squash” round is more technically known as a High Explosive Plastic or HEP round. Where a HEAT round uses the concentrated effect of the explosive warhead to burn through the target’s armor, and the Sabot uses kinetic energy to simply punch through armor, the HEP was designed to destroy tanks without ever even penetrating their armor.

HEP rounds consist of a very thin casing containing plastic explosives. When the round strikes the side of an enemy tank, it flattens against the outside of the tank’s armor. Imagine pressing a well chewed piece of gum against a wall with your thumb. A fuse in the base of the round causes the plastic explosives to detonate, forming a shock wave that travels toward the armor. This shock wave is designed to cause what is called “spalling.” As the shock wave travels through the armor, parts of the armor on the back side break off and fly through the inside of the enemy tank. This spall can kill or wound crewmen, rupture hydraulics, shatter electronics, and ideally ignite fuel and ammunition onboard.

During a period of time in the 50s, HEP rounds were very popular. HEAT rounds were limited in their penetration since penetration is a function of the diameter of the round. US tank guns at this time were only 90mm, giving an approximate penetration against armor of about 500mm.  The discarding sabot round hadn’t been widely adopted (kinetic penetrators don’t work very well from rifled barrels). So the potential of HEP rounds to defeat enemy armor made them very attractive. And as a bonus, they were very simple and cheap compared to other rounds. They also have the benefit of being very effective against bunkers and buildings.

But advances in metallurgy made the HEP round much less likely to successfully destroy enemy armor. By face hardening armor, and leaving the back side of armor less brittle, spalling was less likely to be sufficient to destroy the target. Other means of defeating spalling were also fairly easy to apply. For instance, on board the Bradley, the interior of the troop compartment is lined with panels of Kevlar to catch any spall. This is more to catch any spall from RPG rounds, but the principal is the same.

Currently, the M1 with its 120mm main gun doesn’t use a HEP round, but the Mobile Gun System variant with its 105mm main gun does have one available. This reflects the MGS role as primarily an infantry support weapon, as opposed to an anti-armor platform.

Operation Flintlock – Sixty-seven Years Ago

On this day in 1944, a massive armada began landing US Army, Navy, and Marine Corps personnel on the islands of Kwajalien Atoll, in the central Pacific Ocean.  Allies used the code name “Flintlock” for the operation.  Over the next seven days, the force dislodged, and for all practical purposes annihilated, the Japanese garrison and gained control of the world’s largest coral atoll.  As result, the US drive across the Central Pacific gained another base, extending land-based air coverage out towards the next objective – the Marianas Islands.

Map of Kwajalein

A landing force mostly comprised of the Army’s 7th Infantry Division landed on Kwajalein Island (on the southeast tip of the atoll in the map above) with the objective of an airfield there.  Meanwhile the 4th Marine Division landed on the large island concentration of Roi-Namur in the north to secure Japanese facilities, including another airfield, there.  The somewhat seasoned 7th Infantry had seen prior service in the Aleutians, but was making its first landing in the warmer Central Pacific.  Flintlock was the 4th Marine Division’s first landing (first of four within the next thirteen months!)  Both groups committed just over 20,000 combat troops each.  Defending the Atoll were about 8600 Japanese.

Initial landings on December 31 occupied lightly defended minor islands in the Atoll, to secure landing craft passages for the main landings and to provide firing positions for divisional artillery batteries.  The main landings started on February 1.  After some confusion with landing craft, the Marines secured the beaches at Roi Island and moved inland with deliberate speed.  Remarkably within 27 hours the Marines had secured the major islands in the north, at the cost of 195 killed and 545 wounded.

Clearing a Pillbox on Kwajalein

Observers described the Army’s landings in the south as nearly flawless, among the best conducted in the entire Pacific War.  Terrain constricted movement, and the 7th Division slugged through several pillbox defense complexes over the next few days.  By February 4, save some mopping up, the island was in American hands.  The Army division lost 177 killed and 1037 wounded.  The two forces completed Flintlock with a few additional landings, but by February 8, garrison troops arrived to convert Kwajalein into a major new American base.  Of the entire Japanese garrison (including some Korean laborers), only 265 surrendered.

Aftermath of Battle - Sherman transports a Japanese Tank

The “lessons learned” from Operation Flintlock are many in number.  But three deserve discussion here, as they pertain to military operations (and other endeavors) today as they did then.

First, prior to the operations, the Marines and Army troops practiced… and practiced… and practiced.  The 7th Infantry setup mock Japanese bunker complexes on Oahu, Hawaii based on experience at Tarawa.  These drills paid off during the landings, as the troops moved off the beach, and proceeded to reduce enemy defenses.  Smart, directed training offered a substitute for experience in the Kwajalein landings.

Second, coming behind the long running campaign at Guadalcanal and the nearly disastrous battle of Tarawa, the US Army, Navy, and Marine Corps proved rather adaptable.  Instead of differing doctrine changes to those back in the states, commanders and staff in the combat zone worked out new ways to work around enemy defenses.  Naval ships moved closer inshore to provide gunfire support, and in heavier quantities than before.  Aviation assets learned to provide pinpoint close air support.  The services learned beachhead traffic management.  Logisticians defined “combat loading” procedures.  And the list goes on.  In short, the Americans “learned” in the field and applied those lessons directly to the next action.  This aspect of the “American way of war” continues to this day, with a force which time and time again proves adaptable to the situation.

Lastly, flying in the face of nearly two-hundred years of inter-service rivalry, the Army-Navy-Marine team worked as … well … a team!  At Kwajalein, a Navy Admiral in charge of the operation brought a ground force under command of a Marine general which included a full Army Division (and then some).  Flying long range cover for the entire operation were some fourteen squadrons from the Army Air Forces (gotta work in the USAF somehow here!).  Flintlock was a true joint operation.

Today Operation Flintlock is but a footnote to the larger history of World War II, sandwiched between Tarawa and the “Great Marianas Turkey Shoot” in the books.  Of note, historian S.L.A. Marshall conducted one of his first “oral histories” compiling accounts directly from the soldiers in action.  The resultant work, published as Island Victory: The Battle of Kwajalein Atoll, stands as a landmark for the practice of military history, but also one of only a few studies of the action outside official histories.

I would encourage those interested in this early “joint” operation to read the Army “Green Book” covering the campaign or Volume VII of naval historian S.E. Morrison’s History of United States Naval Operations in World War II.   Marshall’s book, while important, is like many of his works – a labor to read!


The Rifle Platoon

The basic building block of combat power is the infantry, and in the infantry, the basic building block is the rifle platoon. The platoon is the smallest element led by an officer, and is usually the smallest element which may be assigned a mission separate from its parent unit. It is also the smallest unit for which a Field Manual is published. Field manuals are the operator’s manual for how to organize, train, lead, and fight a particular unit. The field manual describes the organization and most common missions that a  unit may be assigned. For for the rifle platoon, the Field Manual is FM 7-8. For the purposes of our discussion, we’ll be discussing “Infantry platoon” as opposed to Mechanized Infantry mounted on Bradley Fighting Vehicles or a Stryker Infantry platoon mounted on Stryker Infantry Carrier Vehicles. The “Infantry platoon” generally describes platoons assigned to light infantry units, airborne, air assault, and Ranger units. While there are some very minor variations in the organization of these units, the fundamental organization and employment is close enough that you should be able to understand what how an infantry platoon is organized and employed.

For today, we’ll limit our discussion to the organization of the platoon. Later, we’ll explore how that platoon is employed, in the attack, defense, stability and support operations, and then we’ll look at the leadership challenges that face a young lieutenant leading his first platoon.

One of the little oddities of Army life is that an infantry platoon isn’t called an infantry platoon. It’s called a Rifle Platoon. This distinguishes it from other platoons in the infantry company and battalion.

The Rifle Platoon, like most combat units,  is a triangular organization. That is, the headquarters for the platoon leads three subordinate rifle squads.


The platoon is lead by a Lieutenant, known as the Platoon Leader (PL). Lieutenants straight from training at the Infantry School’s Officer Basic Course are expected to step directly into this leadership role.  As his assistant, he has a senior infantry NCO, usually a Sergeant First Class (SFC/E-7), serving as the Platoon Sergeant (PSG).  The rest of the platoon headquarters consists of one or two Radiotelephone Operators (RTO), one for the PL, and usually one for the PSG. Normally, all these people are armed with the M16 or M4.

The main strength of the platoon resides in its three Rifle Squads. These three squads are identical. Each squad is lead by a Squad Leader (SL), normally a Staff Sergeant (SSG). Each squad is also broken down into two fire teams. Each fire team is lead by a Team Leader (TL), normally a Sergeant (SGT/ E-5). Squad leaders and team leaders are armed with the M16 or M4.

Each of these fire teams has the TL, a Squad Automatic Rifleman or SAW Gunner equipped with the M249. There is a Grenadier, armed with the M203 Grenade Launcher mounted on his M16 or M4. And finally, there is a Rifleman, armed with either the M16 or the M4.


The last element of the rifle platoon is its heavy weapons, usually organized into a 4th squad known as the Weapons Squad. There is a SSG squad leader, and two medium machine gun teams. The medium machine gun team has a gunner, armed with the M240, an assistant gunner armed with either the M16 or M4.  Most Weapons Squads also have two anti-armor teams, each with a Gunner, armed with the M16/M4 and the Javelin anti-tank missile, and an assistant gunner, armed with the M16/M4 and carrying a spare missile.

Thus, the basic Rifle platoon has an authorized strength from about 35 to 42 people. For the young soldier, the platoon is his family, his home. He lives with them, eats with them,  trains with them, and usually socializes with them to a fair extent. You might think of his squad as his immediate family, and the rest of the platoon as the close cousins. Many soldiers will spend an entire enlistment assigned to one platoon the whole time. While it is usual to stay in one platoon, it is not unusual to be assigned to a number of duties within that platoon as time goes on. My first enlistment was spent in one platoon, but during a nineteen month period, I served as a rifleman, anti-armor specialist, automatic rifleman, assistant machine gunner, machine gunner, grenadier, and RTO.

A little about leadership and training at the platoon level. The PL is responsible for everything his platoon does or fails to do. He is responsible to ensure both that the soldiers assigned know their individual tasks and duties, such as how to maintain their weapons, and their collective tasks and duties, such as how to perform “the Rifle Platoon in the Attack.”  The smart young Lieutenant will use his Sergeants to the greatest extent possible. The team leaders and squad leaders generally train the solders on individual tasks, under the supervision of the PSG. And squad level tasks, such as movement formations are taught by the NCOs as well.  And as the young PL is there to learn as well as to lead, he’ll gladly turn to his PSG for guidance and learn from his experience. No platoon leader should be giving orders to privates. That’s why he has NCOs assigned to him. Normally, the PL issues orders either directly to the squad leaders, or to them via the Platoon Sergeant. The Squad Leaders in turn use their Team Leaders to execute those orders.

The three squad structure of the platoon is designed to give the platoon flexibility in engagement. In the attack (which we’ll cover in greater detail in another post), the platoon leader may choose to lead with one squad, holding two squads in reserve to reinforce or exploit success. Alternatively, he may choose to lead with two squads, and only hold one in reserve. We’ll cover that decision making process in a later post as well.

Finally, a bit about organization in the real world. The above organization is the approved “book solution.” But it is very rare that a platoon will ever actually be at full strength. People are almost always detached for schools or reassignment, out sick or injured, or loaned out to a parent unit for some duty. And often, the Army just doesn’t have enough people to assign enough troops to fill every unit.

When a platoon is short-handed, it is critical that the key leadership positions and weapons be manned.  The weapons squad is almost always fully manned. What usually happens is that the Rifle Squads end up short changed. In that case, usually the Rifleman position is left unmanned, with the Automatic Rifleman and Grenadier positions manned first. In some very extreme cases, the platoon may operate with only two rifle squads. At one time, I served in a light infantry platoon that was so short on personnel that after manning the weapons squad, we only had enough soldiers left to have one rifle squad, but with three fire teams. Everyone in this squad was armed with either the grenade launcher or the M249 SAW.  This is hardly the way things were supposed to be, but you have to make do with what you have.

Finally, when actually deployed to the field, the platoon is always augmented with attachments from its parent and supporting units. Each platoon has a medic attached from the battalion’s medical platoon. He normally moves with the Platoon Sergeant. There is also an Artillery Forward Observer team attached from the supporting artillery unit. The Forward Observer also brings with him his own RTO to communicate with the artillery and mortars. The FO team is glued to the platoon leaders hip. The help him plan for and call fire from supporting weapons.

The speech not needed

Roamy here.  I’m finishing up my series of posts by linking the speech William Safire wrote for President Nixon in case Apollo 11 ended in disaster. 

These two men are laying down their lives in mankind’s most noble goal: the search for truth and understanding. They will be mourned by their families and friends; they will be mourned by their nation; they will be mourned by the people of the world; they will be mourned by a Mother Earth that dared send two of her sons into the unknown.
In their exploration, they stirred the people of the world to feel as one; in their sacrifice, they bind more tightly the brotherhood of man. In ancient days, men looked at stars and saw their heroes in the constellations. In modern times, we do much the same, but our heroes are epic men of flesh and blood.

RTWT here.  Makes me wonder if Neil and Buzz (and Michael Collins, for that matter) wrote letters to their wives in case they didn’t come back.

The astronauts know it’s dangerous, yet they go anyway.

Armstrong (on left) and Aldrin setting up the U.S. flag on the Moon.
Aldrin and some of the experiments set up on the moon. The center one, between Aldrin and the U.S. flag, is the Lunar Laser Ranging Retro-Reflector. It still works.

The Japanese Ontos?

Having discussed the Marines’ Ontos, seems only fitting to mention a very similar vehicle built at around the same time in Japan.

Type 60 Self Propelled Anti-Tank Gun

The Type 60 Self-Propelled Anti-Tank Gun (SPAT) evolved from an early 1950s requirement for the Japanese Self Defense Forces.  Emphasis on DEFENSE.  During the Korean War, the United States encouraged Japan to form a military force to defend the island nation.  The most likely threat in any conventional war was an amphibious or airborne force landing to secure the various straits connecting Russian or Chinese harbors to the Pacific sea-lanes.  As such, the Japanese needed a highly mobile force to contain a moderately armored opponent.  Requirements called for light-weight vehicles capable of rapid transport by train.  Doctrine stressed ambush type tactics to contain then throw back enemy invasions.  Concurrent projects pursued a main battle tank and a self-propelled anti-tank weapon optimized for Japanese requirements.  Both projects proceeded with some deliberation through the 1950s.

SS1-Revised Prototype with Four Rifles

SPAT prototypes from Komatzu Manufacturing (identified as MI or SS1 in some sources) and Mitsubishi Nippon Heavy Industries, Ltd (noted as MII or SS2) rolled out in 1956.  The Komatzu offering used a front mounted 105hp diesel engine, while the Mitsubishi had a 110hp engine in the rear of the chassis.  Both featured two 105mm recoilless rifles (a Japanese derivative of the US M27 recoilless rifle) in a limited traverse mounting.  After testing, Komatzu delivered an additional prototype, the SS1-Revised, with four 105mm rifles.  Mitsubishi delivered the SS-3 with five road wheels.  Then a fourth experimental batch named SS-4, with two M40 106mm Recoilless Rifles (same as used on the M50 Ontos), arrived.  The SS4 also used a more powerful 6-cylinder 150hp diesel engine, mounted in the front.  This emerged as the optimum configuration, and entered series production in 1960 as the Type 60.  In some regards, the Type 60 hearkened back to the “Tankettes” of the 1930s.

Comparison of Production Type 60 (left) and SS1-Revised (right)

Just like the Ontos, the Type 60 used .50-caliber spotting rifles to aid the aim of the main guns.  Also like the Ontos, the Japanese SPAT had a crew of three – commander, loader, and driver.  But unlike the Ontos, the Type 60’s rifles sat in a retractable turret to reduce the vehicle’s height.

Type 60 Self Propelled Anti-Tank Gun

When retracted, the turret traversed only 10 degrees left or right, with an elevation of 10 degrees and depression of 5 degrees.  Deployed in the firing position, traverse increased to 30 degrees, elevation to 15 and depression to 10.

Front View of Type 60

Note also the part welded and riveted construction. The front hull was sloped somewhat, but the sides were vertical. Overall, protection matched that of the Ontos, with only 12mm of armor to defend against small arms and artillery fragments.

Rear View of Type 60

Ammunition lockers provided six rounds. And like Ontos, the crew had to dismount to reload after firing. (And go to Toadman’s Tanks for a good walk-around of the Type 60.)

Type 60 in the Snow

In the field, the eight ton Type 60 reached 34 mph on roads. Turret retracted, the SPAT stood only 4.5 feet tall. Just over 7 feet wide and 12 feet long, the Type 60 was a compact fighting vehicle.

Type 60 During Training Exercises

Komatsu produced over 250 Type 60s.  After the initial “Type A” production, “Type B” appeared with some structural reinforcements.  In 1974 a “Type C” entered production using a liquid-cooled engine with the same power ratings. The only other major modification considered was an auto-loader.  But that was quickly dismissed as overly complicated for the small vehicle.  As late as 2001, 140 of these SPATs remained in service.  But officially all were retired in 2008.

Type 60 on Maneuvers in 2006

Normally, I’d close out with a video or two.  But the only clips I could find feature this guy:

Occasional movie appearances were the highlight of the Type 60s service.

One might easily dismiss the Type 60 as a “knock-off” of the Ontos.  I wouldn’t be so quick.  As mentioned before, the Ontos sprang from US Army requirements for an airborne anti-tank weapon system, only later to see service as a lightweight anti-tank system for the Marines.  Designers optimized the Ontos with enemy counter attacks against envelopment operations (fancy way of lumping airborne and amphibious assault into one category).  In Japan the Type 60 was the defender countering just such envelopment.

As often occurs with weapons development, dissimilar requirements lead to very similar weapon systems.

What’s up next

I was planning on showing a quick clip of a firefight in Afghanistan. Then I decided to show the clip, and use it to illustrate the squad combat drill, and platoon battle drills. But then I realized, for that part of my audience that isn’t familiar with some of the underlying concepts, I have to explain a little more about what a platoon is, how it is organized, and how it is deployed.

So I’m gonna start a series based on FM 7-8, the Infantry Platoon. For my readers familiar with this basic organization, I ask your forbearance and patience. I’m not going to copy the whole manual and train civilians to lead a platoon, but I do hope to give them a better understanding of how the basic combat arms unit works.

For my readers who are not familiar with the concepts behind this, I’ll try to avoid jargon and make it as simple to understand as possible. But if you do have questions, please don’t hesitate to ask, either in comments or in an email. The entire original purpose of the blog was to help make the Army more transparent to civilians with little or no contact with the Army.

Having said that, I’m going to be on the road today, and probably face limited access for a few days. Please be patient.

Not forgotten

Roamy here, continuing my series of posts on remembering fallen astronauts.  I mentioned in the Day of Remembrance post that it’s not just for the crews of Apollo 1, Challenger STS-51L, and Columbia STS-107, but also the astronauts who died while training for flight or on official NASA business.  I recommend The Astronaut/Cosmonaut Memorial Web Site for more information about Theodore Freeman, Charles Bassett, Elliot See, Clifton Williams, Robert Lawrence, Michael Adams, and Manley “Sonny” Carter, Jr.  The website includes info on other astronauts who died in non-work-related plane crashes, e.g. Stanley David Griggs, who died while piloting a WW2-era trainer in an air show near Earle, Arkansas.

Bassett and See had been picked to crew Gemini 9.  They were flying to St. Louis in February 1966 to train for two weeks at McDonnell Aircraft in a building 1,000 feet from the runway at Lambert Field.  Snow and poor visibility led to the two crashing into the very building that held their Gemini capsule. 

Freeman and Williams died in separate T-38 accidents.  Lawrence died in an F-104 crash. Mike Adams earned his astronaut badge by flying above 50 miles altitude on his final and fatal X-15 flight.

Astronauts Sonny Carter and Kathryn Thornton during STS-33

I met Sonny Carter in 1990.  Each Shuttle crew usually travels to each NASA center to meet the workers, sign autographs, talk about their mission, and remind us that there are human beings riding on the vehicles we’re working on.  Sonny stood out for me not just because he was selected for the International Microgravity Laboratory mission, and I had worked on one of the experiments, but also because he was from Macon, Georgia, and he spoke with an accent that sounded like home.  He was killed in the crash of Atlantic Southeast Airline Flight 2311 in Brunswick, GA, which also killed former senator John Tower of Texas.  The Neutral Buoyancy Laboratory at Johnson Space Center was renamed the Sonny Carter Training Facility in his honor.

May they all rest in peace.

Marines Ready for Egypt Rescue Mission – Swampland – TIME.com

In a follow on to my earlier post, let’s not forget that there are about 90,000 US citizens in Egypt. If things really go to pot there, the Marines in the area may be tasked to conduct a NEO, or Noncombatant Evacuation Order. It’s unlikely, but you can bet contingency plans are being made.

The U.S. Marines have a pair of warships — the USS Kearsarge and the USS Ponce — just hanging around the southern end of the Red Sea waiting to see if they’re needed to rescue U.S. diplomats and citizens from Cairo.

via Marines Ready for Egypt Rescue Mission – Swampland – TIME.com.

Via Information Dissemination