Category Archives: 120mm

120mm for Air Defense

When you mention a 120mm gun today, virtually everyone thinks of the main gun of the M1 Abrams family of tanks. And rightly so. It’s an impressive weapon. But did you know that from the mid-1940s to the early 1950s there were more than a few 120mm guns guarding the US?

The US Army began World War II with the M3 3” gun as its primary heavy antiaircraft gun. The M3 was itself a slightly improved version of the M1918 fielded for World War II, and was clearly facing obsolescence. It lacked the ability to reach the high altitudes routinely used by enemy bombers, and didn’t throw a very powerful shell.

Soon the excellent M1 90mm anti-aircraft gun replaced it.

But as good as the M1 90mm gun was, it still lacked the range and altitude needed. Toward the end of the war, the Army finally fielded the massive M1 120mm heavy anti-aircraft gun. While a few batteries were sent to the Pacific before the war ended, it doesn’t appear any actually engaged Japanese aircraft.

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The beginning of the Cold War raised the spectre of Soviet bombers laying waste to American cities with nuclear weapons. Accordingly, a very high priority was given to air defense of the continental US. The Air Force fielded many squadrons of fighters. And pending the development of guided missiles, the Army placed batteries of 90mm and 12omm guns to protect our cities.

A typical 120mm battery had four guns. The guns were automatically directed by the M10 director system, which in turn used information from the SCR-584 radar, or a similar gun laying radar and the M4 gun computer.

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Batteries also protected sensitive sites such as the Panama Canal.

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By the mid-1950s, the M1’s ability to destroy high speed bomber targets was marginal. As rapidly as possible, gun batteries were replaced by Nike Ajax guided missile batteries.  Today, the M1 is but a faint memory.

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Mortar Monday (I meant to post this yesterday)

So, 5/20IN hosted the Japanese Ground Self Defense Force to a mortar live fire at Yakima Firing Center recently. Lots of 120mm goodness going on.

Here’s the short PAO take.

And here’s the extended version. I love that piiiiiing! that 120mm mortars make when firing. Gives me a warm fuzzy.

And while I tend to think of the 120mm as a big mortar, the Soviets and the Israelis have used 160mm mortars. And then… there’s this:

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Battle for Berlin, 1945

This week marks VE Day, commemorating the Victory in Europe over Hitler’s Third Reich.  The last and perhaps the most savage battle was for the German capital of Berlin.   This from the Battlefield series, which was aired weekly on Far East Network (“Forced Entertainment Network”) when I had an artillery battery in Okinawa in 1996.   The entire series is superb, and if you look, you can find most of them on line.  They are also available on DVD.   They contain a pretty good description of the higher tactical through the strategic picture, and have enough detail and technical stuff, but not too much.

Since the series was made, Russian archives have been explored more completely, and the number of Soviet casualties have been scaled up more than two-fold, from the 305,000 quoted in this episode, to nearly 700,000.   Note the ever-present use of artillery and mortars, rockets, and field guns, even in an urban environment.   The episode is 116 minutes, roughly the time one spends clicking on all of Mav’s aviation links and cool pictures and videos and stuff.   So get your Eastern Front geek on, and watch it.  You know you wanna.

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Filed under 120mm, Air Force, armor, army, Around the web, Artillery, guns, history, infantry, planes, Splodey, Uncategorized, veterans, war

BIG! Mortars

We’ve written before about mortars being the infantry commander’s “hip pocket artillery.”* And in our Army, mortars are infantry weapons, separate from the Field Artillery.  Currently, our Army fields 60mm, 81mm, and 120mm mortars.

But that doesn’t mean there aren’t larger mortars.  Israel and several other countries use 160mm mortars. And the current largest mortar in service is the Russian 240mm mortar.

That’s a pretty hefty tube.

It’s odd to see a weapon that has a rotary magazine and power loading and yet the each round has to have its primary and booster charges hand applied. I mean, really? Tying the “cheeses” on with string?

Looks like some guided and rocket assisted shells in there too.

*well, Infantry, Armor and Cavalry- basically each ground maneuver battalion has its own mortars.

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The Care and Feeding of Co-authors.

Normally, I like to make fun of Marines. And I like to make fun of
Artillerymen. I especially like making fun of Marine Artillerymen.

But if I pick on URR too much, he pouts and doesn’t post much. Which means, I would have to, and what’s the point of having co-authors, but to pick up my slack?

And Roamy, bless her, likes some splodey/shooty. It’s not like I pay them for content, so once in a while, I have to be nice to URR and Roamy. Here, I’mma kill two birds with one stone.

The Marines will never have anything approaching the numbers of guns Army artillery has. Yes, in Iraq and Afghanistan, the need for tube artillery has been fairly sparse. But in a near-peer conflict, a war of maneuver, artillery will be as key as it always has been. One of the linchpins of a strategy of maneuver is denying that very maneuver to your enemy. And artillery fire is a key component of that. The old definition of maneuver was “fire and movement” and artillery provides the “fire” while infantry/armor provides the movement.

It’s not so much that the Marines are dim and not smart enough to buy a lot of artillery. They are. But they face two important constraints on the amount of artillery they can field. First, all their artillery pretty much has to be air transportable by helicopter. And given the very limited number of CH-53E’s available, if at all possible, they want systems that can be lifted by the smaller, more numerous MV-22B. Second, the Marines are an amphibious force, which means they have to travel on the amphibious shipping provided to them by the Navy. As big as those ships are, there aren’t a lot of them, and further, there is a fixed, finite space available for equipment. Finding a balance between tanks, artillery, amphibious assault vehicles, logistical trucks, Humvees and all the other stuff a Marine Expeditionary Unit needs to take along is one of the headaches Marine planners face on a regular basis. So finding an artillery system that uses less space, and weighs less and, in a perfect world, takes a smaller crew, is a key priority. So the Marines are buying the EFSS 120mm mortar system, in lieu of the traditional 105mm gun howitzer.

In the Army, all mortars, even the 120mm, are Infantry weapons, organic to Infantry and Armor/Cav organizations. But for the Marines, if you’re going to use a mortar as your primary direct support system, having the artillery man it makes sense.

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One Very Dangerous Gerbil

When DPRK dictator Kim Jong-Il died in December of last year, his 27-year old (we think) son, Kim Jong-Un succeeded to the seat of power.  Believed to be a soft and callow youth unfamiliar with the dangerous intrigues of the power elite in North Korea, Kim Jong-Un was described by a Western intelligence analyst this way:   “In a pit of snakes, KJU is a gerbil”.     His long-term prospects were uncertain, to say the least.

Perhaps, just perhaps, there was significant underestimation of the Dear Boy who is now Dear Leader.  It would appear that some thirty senior DPRK officials, including a substantial number in Army leadership, have been “removed”.   We are looking at a full-fledged purge.   The latest, the Guardian tells us, is the execution of Kim Choi, former Deputy Minister of the Army.  His means of execution?  Mortar round.  No trace to be left.  (In all likelihood, if the 82mm pictured in the Guardian article was the ordnance used, there would be plenty of traces.  So maybe it was a 120 or 160?)  Reason?  Carousing during the official mourning period of his father.  (So much for lifting a Guinness, “for strength”!)

The West (and South Korea) had hoped that the young dictator would be more inclined to be a reformer who could reach out to the West and attempt to alleviate the miserable privations of DPRK’s populace, and lessen the pariah status of his country in the region and world.    Kim Jong-Un’s actions don’t necessarily rule out such an inclination, but they do show that he certainly was a fast learner in the game of power consolidation, and has no trouble employing the traditional tactics of political purge, prison, and execution of military and political rivals on flimsy charges.

My guess is that the snakes are considerably more nervous than they were ten months ago.   Young Kim has a semi-hot wife, apparently, and even if the family photo has a slight hint of mortal terror (whose don’t?), he seems to be getting comfortable with the trappings of his office as Brutal Dictator Dear Leader.

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The USMC Expeditionary Fire Support System (EFSS)

In February of 2011, the USMC Expeditionary Fire Support System was employed in combat in support of Battalion Landing Team 3/8 (26th MEU) in Helmand Province, Afghanistan.   The combat deployment was more than a decade in the making, the culmination of development which began in the late 1990s.  The requirement EFSS was intended to fill goes back at least another decade, to the final retirement of the venerable M101A1 105mm Light Howitzer from the USMC inventory, a cannon that had first entered service before World War II.

Concept of Employment

EFSS, along with the HIMARS rocket system and the M777A1 155mm Towed Howitzer, is intended to be part of the “triad” of ground fire support systems for the United States Marine Corps.   EFSS is conceived to be a part of the assault echelon of ship-to-shore movement, and provide maneuver forces with close ground fires until tube artillery comes ashore in the on-call waves, perhaps as much as 24-48 hours after H-hour.

The EFSS is being fielded in the Artillery Regiment of the Marine Division, which is a bit of a paradigm shift from more recent previous heavy mortar efforts by the USMC, but not unprecedented, as will be discussed below.

System Components

The EFSS is built around the RT120/M327 rifled 120mm mortar.    The mortar, carriage, and baseplate weigh 1,780 pounds, and has a crew of four.  Range with standard munitions is 8.5km.  GPS-guided Precision Extended Range Munitions (PERM) are capable of ranges of 17km, with a reported circular error probable (CEP) of 20m.  Projectiles vary in weight from approximately 36 to 42 lbs.

The prime mover for the RT120 is the Growler Internally Transportable Vehicle (ITV), based on a modified M151 Jeep concept, but with a sophisticated variable suspension system and dimensions tailored for internal transport, as the name implies, in the V-22 Osprey.  The Growler has a four-cylinder turbocharged diesel engine that generates 180 horsepower, is equipped with four-wheel drive (with a selection for rear-wheel drive only), and is capable of towing 2,000 pounds cross country.

The EFSS consists of the above-mentioned mortar, two ITVs, with each respectively towing the mortar tube, and an ammunition trailer which has a bustle rack for 36 ready rounds.  Tactical and vertical mobility have been emphasized, in order to ensure equal mobility to the maneuver force being supported.

Criticisms

The EFSS has not been without controversy.  Much of it surrounds the Growler prime mover, which has been specifically designed to fit into the very restricted internal cargo area of the V-22 Osprey.    The cost per unit is estimated to be over $200,000.   With a narrow wheelbase and limited ground clearance, true cross country capability is in question.   The vehicle is prone to rolling in turns, and may have trouble navigating the rugged terrain in undeveloped areas in which employment is possible.   Additionally, the Growler offers no ballistic protection for its crew.  Open on three sides, it is vulnerable to small arms, fragmentation, and the IED threats that have become so familiar in the last decade.   All valid criticisms, and requiring of the assumption of significant risk in employment.

For my part, the EFSS is at best a hybrid and therefore suboptimal solution.  This is not the first foray for the Marine Corps into the idea that a heavy mortar might replace a light howitzer capability.  In the early 1960s, the M30 4.2-in (107mm) chemical mortar was mounted on a surplus 75mm pack howitzer carriage, and mated with a recoil system to ease emplacement and increase range.

The M98 Howtar*** was the result, and was briefly fielded in Vietnam with Marine Artillery units.  However, with its still limited range when compared to the howitzer, and with similar mobility requirements, the M98 proved significantly less suitable than the 105mm howitzers already in service, and not a substantial upgrade from the standard “four-deuce” in service with Marine Infantry units.

The EFSS has similar limitations.

First, the weapon is a mortar, and incapable of low-angle fire or direct fire.   High angle fire is a significant challenge in fire support coordination with fixed and rotary wing air assets that comprise fully half  of the USMC combined-arms team and will be of critical importance in supporting operations ashore before tube artillery and HIMARS can be landed.

Second, unless the preponderance of ammunition is of the PERM variety, which is a doubtful proposition due to costs, EFSS has limitations in range (8.5km)  that require it to be well inside the range fans of a host of threat weapons systems in order to successfully prosecute targets.

Third, the rate of fire of the RT120/M327 is around 6 to 8 rounds per minute, relatively low for a mortar system, which limits the volume and weight of fire that EFSS can provide.

A more appropriate solution to light and mobile fire support would seem to be that of a lightweight 105mm howitzer, using similar weight-saving materials (titanium) and designs that allowed the M777A1 155mm towed howitzer to weigh slightly over half (8,800 lbs) what the M198 155mm (15,780 lbs) system tipped the scales at.    A 105mm howitzer weighing 3,000-3,500 pounds, capable of firing more lethal and extended range modern munitions, equipped with course-correcting fuses, would be a great enhancement to the Landing Force Commander, providing a much more robust and capable fire support system for minimal additional logistic and mobility requirements.

That said, the EFSS is infinitely better as a fire support system than what existed for that niche previously, which was nothing.   It is a recognition that, despite our recent low-intensity conflict/COIN experience, the modern battlefield will see an increased emphasis on ground fires.  This  is already true of those areas in the littoral where our adversaries are building Anti-Access/Access Denial (A2AD) capabilities with an eye towards thwarting US power projection options.

(***Note, the above photo of the M98 Howtar was taken on the quarterdeck of 10th Marines HQ at Camp Lejeune.   The Notre Dame Leprechaun is undoubtedly the work of Col Chris Mayette USMC, who commanded the regiment at the time the picture was taken.   There is no substantiation to the rumor that the Howtar disappeared when he turned over command, or that a similar one now adorns his living room in his current location…)

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