"Effect of indirect artillery fire" Topic

In almost all rulesets on 1914-1945 which I have read, indirect artillery fire is more deadly, the bigger the guns are. I have always wondered if that was true. In WW1 the french preferred the quick firing 75 mm since it was more deadly in the open as opposed to larger guns. Only when the war moved to fortifed positions and counterbattery fire did the big guns gain prominence.

Recently I read the artillery notes on the battlefrontWW2 homepage with tables of neutralisation effects from the US army. Here it was stated that the bigger the guns, the longer time was required to neutralize enemy infantry – but the template would be bigger. This makes sense to me…

So in wargame terms should heavy artillery barrages be deemed less effective but able to penetrate better cover/fortifications and shoot longer, thereby enable counterbattery fire?

Depends how detailed you want to get. In some rules heavier FA may only fire every other turn. But yes they may have a bigger template and/or more "firepower" under that template. And the fact that they have more firepower under that template would reflect their ability to " penetrate better cover/fortifications ". Plus the heavier guns may use more than one or bigger templates. E.g. the basic chart we generally use for basic FA & Mortars :

Barrage Table [using d6(s)]

Light –
Vehicles – No effect
Inf – 5+ to hit, Sav Mod 0

Medium –
Vehicles – 6+ to hit, Crit Hit – 5+
Inf – 5+ " " , Sav Mod -1

Heavy –
Vehicles – 3+ to hit, Crit Hit – 3+
Inf – 4+ " ", Sav Mod -2

Special Rules for certain weapons may use more than one template or bigger template(s). Plus some heavier weapons may only fire every other turn.

and shoot longer, thereby enable counterbattery fire?

That is a slippery slope again depending on the detail you want/have. But rules are/can be made for CB Fire. Which could get quite detailed.

E.g. :

FA must be on Fire/CB Orders.

Many Only fire at FA that has previously fired that turn.

To CB roll 1d6: 1-3 cannot CB … 4+ can CB. (You may not always be able to discern where the fire is coming from. And/or my be out of range.) …

Also note you may have to see where fire goes/scatters if it does not hit target. I.e. roll for scatter.

K.I.S.S.

You actually illustrate my point – the rules you use make heavy artillery more effective against infantry in open terrain – the opposite seems to be the case….

The K.I.S.S approach would be the same effetct for light and heavy artillery but better ability to harm cover/armour for heavy??

Artillery when used right is devastaing I watched it go in.

Not just "more effective" Sparta. Sometimes it's a question of being effective at all. I'm remembering one incident from Vietnam in which a senior artillery officer, who remembered dealing with Japanese-held islands in WWII had to explain to the young gun bunnies that no amount of 155 fire was going to work against certain Communist fortifications: it was bring in the 8" guns or go home.

Against targets in light cover, more, smaller shells will work better than fewer, bigger ones. Against targets in earthworks in particular, you want bigger shells with more penetrating power.

Bear in mind that in 1914/15 the vast majority of field artillery ammo was shrapnel, which was almost completely useless against dug in troops and why, by 1918, all artillery fired HE. It is also a matter of usage, a destructive bombardment is fired in a far more deliberate manner than a neutralising barrage or concentration, so has different effects on the receiving end.

Our WW1 rules reflect the differences, for WW2, less so as WW2 arty was so much more deadly. The area of effect for a 155 was the size of a football pitch. As Charles MacDonald noted as he called in a defensive FFE of 155s in front of his company position in 1944 "Nothing is going to survive that".

Overall, the neutralising and destructive effects of artillery are a function of weight of fire (pounds of HE delivered per square yard) and intensity of fire (pounds of HE delivered per yard per hour. There is operations research covering this sort of thing, the Soviets codified in their artillery manuals.

British doctrine in Normandy (and probably before) was that once an enemy was entrenched you needed very big guns and time to do anything. But if you catch targets in the open it was fast response then rate of fire in that first 15 – 60 second period that mattered. Hence the large numbers of 25prds to hopefully catch then stop the enemy.
Long barrages were only really used to fix not really kill the enemy.

The British decision to employ the 25 pounder as the exclusive divisional field artillery piece was to my understanding a pre-WWII decision. It's primary purpose in both defensive and offensive operations was to suppress the enemy, achieved by firing a sufficiently large number of shells per area per minute; 25 pounder could be fired moderately rapidly, and there was a lot of them (72 per infantry division).

The big guns were found in medium and heavy RA regiments that were typically corps level assets.

Tired mammal is spot on! The bulk of casualties from artillery are caused in the opening seconds of a barrage, Troops in the open etc. A lot of modern artillery can burst fire 3-4 rounds then the ROF is reduced.

Artillery is commanded at the highest level and controlled at the lowest, so a British FOO could direct

Mike target – Quick concentration of fire by all the guns of an artillery regiment.
Uncle target – Quick concentration of fire by the guns of a division.
Victor target – Quick concentration of fire by the guns of a corps.
Yoke target – Quick concentration of fire by the guns of an army group

If the game is extremely tactical, where a single round makes a difference, you may have an issue. But in the majority of wargames each turn represents a longer period of time. So, I believe, a larger gun would be just as effective over time, and cover a larger area.

In the Designer's notes for AH's Tobruk it was noted that 25lbers were the preferred guns for attacking infantry, but that it took the 5.5 in guns to knock out Italian fortifications.

You actually illustrate my point – the rules you use make heavy artillery more effective against infantry in open terrain – the opposite seems to be the case….

Yes and no. Light & Med Indirect Fire assets have a higher ROF. So in reality it would appear that it causes more damage to Infantry in the open. I think you are misinterpreting that data a bit. As noted here …

But if you catch targets in the open it was fast response then rate of fire in that first 15 – 60 second period that mattered. Hence the large numbers of 25prds to hopefully catch then stop the enemy.
Long barrages were only really used to fix not really kill the enemy.

With a faster response time and a higher ROF of lighter weapons you will kill more before they get into cover of some sort, etc. Higher ROF = more rounds on target after the first rounds are fired.

Plus Infantry in the open won't stay that way for long. They/we move from cover to cover and seek cover, etc.. Spending a lot of time trying to get something solid between you and all the flying objects on the battlefield.

Again the Light & Medium weapons can generally put more rounds on target quickly, i.e. Infantry in the open. Before they move into cover. Again a higher ROF than Heavies.
But I guarantee you if one Squad in the open is hit by Light/Medium fires. It will take less losses than another Squad if hit by heavy shell(s). As reflected in the chart I posted

Again the blast effect from smaller rounds don't have the firepower, Blast Radius, etc. of the larger obviously.

no amount of 155 fire was going to work against certain Communist fortifications: it was bring in the 8" guns or go home.

As noted Lighter & Med Indirect fires can't do as much damage to fortifications and armor, etc., as the Heavier. I.e. 8" is bigger than 155s. The ROFs of the "Heavies" are generally slower. But the "BooM"/killing power is bigger.

The K.I.S.S approach would be the same effetct for light and heavy artillery but better ability to harm cover/armour for heavy??

No that is too simple … and not really accurate in reality.

As the chart I posted reflects. Heavier rounds will do more damage to everything. Than those of smaller calibers.

And generally any sort of cover will reduce losses somewhat. Even just lying prone. Again, based on the size of the shell.

If the game is extremely tactical, where a single round makes a difference, you may have an issue. But in the majority of wargames each turn represents a longer period of time. So, I believe, a larger gun would be just as effective over time, and cover a larger area.

Yes that is one of the points I was trying to get at.

In the Designer's notes for AH's Tobruk it was noted that 25lbers were the preferred guns for attacking infantry, but that it took the 5.5 in guns to knock out Italian fortifications.

Great game too. That illustrates the fact that lighter weapons have less effect on fortifications than the heavier 5.5.

As obviously the lighter guns, the 25lbers, have less effect on fortifications than the big 5.5 shells. But will do a lot of damage to Infantry.
And again the 5.5 round will pretty much do a lot of damage to everything.

I pretty much stand by that chart I posted. Of course as an Infantry Officer I was trained to call-in Indirect Fires and CAS. And know from training & experience that chart is more accurate than not.

Big (150mm+) rounds are also horribly effective for direct fire. That is why the relatively low velocity gun on an SU152 literally demolished Tigers and Panthers if it hit them. It blew them apart.

Thx for all the great response, it seems to be as I suspected, namely that the point of the big guns is mainly destroying fortifications and long range bombardment.

Thx to Legio4 for the responses – I did not understand your chart since I assumed that the effects was based on a full turn of fire, and therfore I did not appreciate that different ROF could impact the statistics.

So as I see it how we simulate indirect fire depends a lot on how long a turn is in a game. In short turns fire will represent fewer shell and even only single shells from large guns. Rhe would imply that the chance of hiitng with a large gun should be much lower, but a hit more devastating – due to statistical spread of the rounds.

But if we play a game with longer turns, the time taken to neutralize an area is the effect of the battery. I found an interesting table from the US here:

link

The point is that a 6 gun 75 mm battery firing in an converged sheaf neutralizes 50x100 in 30 seconds of initial fire and 155 100x100 in 60 seconds, whereas for sustained fire the numbers are 1 min 12 s for 75mm and 3 min for 155mm. This would to my interpretation mean that a game where you have long turns at a higher level, fx 10-20 minutes turn with each base as a company, the average effect of a heavy artillery barrage vs infantry in light cover would be less from heavy guns? Again most rules at this level seems to put better effect from heavy guns.

Yes, game mechanics, Time scale, etc. will effect how weapons are used in a game. Also note like with that chart. It is a generalization for gaming purposes. As many gaming rules are. And certain type of rounds may have "special" rules. E.g. like tree bursts, point detonating, etc.

the average effect of a heavy artillery barrage vs infantry in light cover would be less from heavy guns?

But again, ROF, Cover and size of the rounds all matter. Based time scale for gaming purposes. Basically a 155 shell with do more damage than e.g. 105 or 75mm shell to Infantry even in light cover. E.g. a wooden or bamboo structure will provide concealment but not solid cover. Generally neither of those type structures will stop much of any schrapnel, etc. Or even small arms for that matter. [Also note: a 50 cal will chew thru bricks like it was peanut butter. But any cover & concealment is better than none. And generally reduce losses.

Again you can put more of the smaller FA and Mortar shells on target in shorter amount of time. Than the larger shells can. And yes the larger shells do much more damage to bunkers, entrenchments, AFVs, etc. Than the smaller rounds. As we saw in some of the examples posted above.

Hope that helps …

Big (150mm+) rounds are also horribly effective for direct fire. That is why the relatively low velocity gun on an SU152 literally demolished Tigers and Panthers if it hit them. It blew them apart.

Yes, very much so. As again in this case size does matter/bigger is better.

Before the Great War started, the French High Command desperately wanted more heavy guns. The rationale was based on observations from the Sino-Japanese War in 1905, as well as awareness of the German developments such as the relatively mobile 15cm heavy howitzers. This was vetoed by the Government, which meant that the French army went to war with a dearth of heavy guns.

All 1914 armies were dominated by field guns, numerically. 'Effectiveness' of indirect fire depended on a number of factors. Field guns, such as the French 75s were less effective when attempting to engage targets in defilade. The flat trajectory meant that shells passed over targets. The same problem affected heavy and super-heavy guns too, though the latter did not appear until after 1914. Howitzers of all calibres were more effective against these targets because of their high trajectories.

By First Ypres, virtually all artillery operated with indirect fire. Attempting to operate in the open under observation was a death-sentence. There is clear evidence that the heavier calibre howitzers were more effective in this role than their lighter counterparts. Even though field guns could fire more shells per minute, there weren't enough guns and ammunition (by comparison to late war) to suppress the enemy in light entrenchments. There certainly wasn't enough firepower to destroy the enemy. It took quite a while for everyone to appreciate that field artillery could still be effective by concentrating on suppressing dug-in enemy, rather than trying to destroy them.

The successes enjoyed by the German attacking forces in First Ypres, such as they were, related to the powerful effects of 15cm howitzer indirect fire – the notorious 'Jack Johnsons'.

Robert

This site will give you a better idea of indirect artillery effectiveness and what you need to destroy underground bunkers.
link

A beaten zone of 100x100 meters is 10,000 square meters.

Let's say an underground bunker is 25 square meters which means it occupies 1/400 of the 10,000 square meters beaten zone. A Russian 152mm round will leave a crater about 25 square meters.

Now figure out the chance a single 152mm round has of landing close enough to damage the underground bunker in a barrage. It does not need a direct hit.

Wolfhag

I would observe that, for whatever analysis was used to justify the French soixante-quinze prior to WW1, or the British 25pdr prior to WW2 (and to rationalize them in the years since) …

During WW2 it was pretty conclusively shown that 100-105mm guns out-performed 75-83mm guns in the light artillery role.

Can we identify any major army that has deployed 75mm class artillery pieces since WW2?

The British Army today doesn't use anything smaller than 105mm for their light artillery. The Russians dropped their 76.2mm and even skipped past 100-105mm and went straight to 122mm in their post-war light artillery. The US Army even dropped 105mm (except in exceptional light weight forms) and now rely on 155mm as the smallest artillery piece.

Why would this be so? Good research shows the higher rate of fire and more bangs per area has higher potential for causing casualties against soft targets.

But ask any infantryman what he has been taught. The moment you stop walking, you start digging. No one doesn't get that message. You dig. You dig dig dig. You get down below ground level. Always. As fast as you can. Every time.

You don't need artillery from 10km away to stop soldiers from walking upright across fields. They don't do that anyways (if they are at all trained). They sprint from cover to cover. Not that cover part? If they stand up you can shoot them with your MG. You don't need 75mm guns with 2 minutes response times for that issue.

But if you want to avoid having them shoot YOU with their MG when you stand up, you need to get at them when they are dug in. You need more than 75mm to do that.

I think all the theories aside, that the issue has been shown by armies "voting with their feet". Larger artillery is more effective. It generates more casualties. It suppresses more defenses. It works better at doing what the army needs artillery to do.

At least that's my read. I am not an artilleryman, nor do I play one on TV. But the evidence seems pretty clear to me, in my TV role as a casual reader of history.

-Mark
(aka: Mk 1)

Larger artillery is more effective. It generates more casualties. It suppresses more defenses. It works better at doing what the army needs artillery to do.

Yep … again size matters …

The Russians have done a lot of analysis and developed formulas for arty destruction and neutralization of targets:
link

Wolfhag

The WW2 Royal Artillery site has tons of info on this, covering all nationalities.

link

I spent a happy couple of hours last night working out how many neutralising in and destructive fire missions various typical WW2 artillery regiments could fire in a day given their typical ammo holdings. A rough idea is that a destructive mission (to inflict 30%) losses on a 300 yard square target which was in slit trenches took 6000 25pdr rounds, while a neutralising mission only took 300… A destructive mission against the same size target in the open took 600 rounds.

Halve the number of rounds for 105mm and a third for 150m+ the bigger rounds weigh ten times as much, so by shell weight are proportionately less destructive. It also means a 24 gun 25pdr regiment is equivalent n firepower to a 12 gun 105mm battalion (roughly). Anyway, thee are lots of tables so you can do your own calculations.

The definition of neutralisation changed postwar as NATO focused on planning for ww3, so these are consistent with wolfhags data, read neutralisation as harassing fire post 1955, and destructive as neutralising.

Martin,
I've run the numbers too and have come to pretty much the same conclusion. One variable is the Time on Target which is designed to surprise the target with an overwhelming short barrage before they can take shelter. The way I see it a ToT barrage in a company level game would pretty much end it as the target would unable to defend itself.

In a game, any attempt to accurately portray a barrage of 50+ shells will result in a game called, "Artillery Commander" but some players really enjoy plotting single rounds against a target. I don't.

The way I'll handle a 50 round barrage against a 200x300 meter area (8x12 inches in my games) is to take a clear transparency and have the player plot the 50 rounds randomly on it with a dry erase marker. Then with a single die roll, we'll determine where the center of the barrage drifted from the desired center. Then we place the clear transparency over the table and can readily determine hits and near misses. Of course this only works against static targets. A barrage like this might take 3-5 minutes during which the attackers' would be able to maneuver or close on the target and the defenders would be keeping their heads down with some observers attempting to detect the attackers. In 3-5 minutes a tank moving at 12kph would advance 900-1500 meters

You also need to take into account the dirt, dust, and debris which is going to severely degrade the defender's observation, especially if the barrage includes smoke rounds. This should not be overlooked. In WWII the US planned to have about 25% of the pre-assault barrage fall in front of the defender's line to insure blocking LOS and to create shell holes for the defenders to take cover in if need be.

Another factor to consider is how quickly the defenders are going to recover from a 1+ hour intense barrage from guns over 105mm and MRL's even if they had good underground defenses. Concussion and having to dig yourselves out of your bunker is going to take time.

If the barrage was timed correctly and lifted as the attackers got to the defender's line, a tank moving at 15kph is going to penetrate into the defender's area at the rate of about 300m per minute. This means that there will be a percentage of defenders exiting their bunkers only to be gunned down and run over by the attackers. This is where the Russian tank riders are dropped off to do their work.

Probably the most playable way to simulate an intensive pre-assault barrage would be to start the attackers a few hundred yards from the defender's line and then each turn each defender attempts to recover and exit their bunkers and determine any causalities when the barrage lifts. The results of the barrage are abstracted. So if you computed the barrage to generate a 20% causality rate you'd check that when they exit. Ideally, you'd get the timing of the attackers advance and defenders exiting.

Setting up medium anti-tank guns after an intensive barrage may be almost impossible. However, this would be a great environment for tank hunters as portrayed in a number of Eastern Front movies.

Wolfhag

Thanks for all the great and relevant response. However, I still have some reservations when it comes to historical game design.

Since the Napoleonic wars gunds have gotten bigger because they got lighter and the grenades starting to have more bang for the same weight, That means a modern gun since ww2 has higher ROF and lower weight than a similar WW1 piece. An obvious reason to choose a larger piece. But if we look at WW1 and 2, defensive barrages against attacking infantry was common – look at the SOS barrages in front of trenches.

I would still argue that for wargaem purposes it is to simplistic to put a heavy piece down as more effective in all situations, and that lighter pieces would be better against attacking/maneuvering troops as seen in WW1 and WW2 on the eastern front/western desert and many other places.

Obviously for modern warfare post WW2 this is different both due to increased unit small arms fire, different infantry tactics and heavier pieces with increased ROF and shorter response time.

I would add CnC into your thinking. As comms and fire control became more sophisticated, the longer range of the big guns meant one battery of 155s could cover the same ground as multiple 105 batteries. Using less manpower and being cheaper to produce.

I agree with Sparta (Greek solidarity in action here!).

The mission of heavy artillery was to deal with field fortifications. Today, any target requiring more dramatic measures than a 6in-8in artillery fire mission can conveniently place a call to tactical air support for a Domino's Pizza delivery of a laser-guided 2,000lb JDAM or some such flavor treat.

In WW1, Domino's Pizza did not exist. 3in field artillery was largely ineffectual against even troops sheltering in a trench line. By late war on the Western Front, reinforced concrete shelters 30-60 feet below ground were not uncommon. The response to these sorts of defensive works can be seen in the artillery orders of battle of th respective contestants. 6in guns were commonplace. 8in, 9.2in, 11in, 12in, all the way up to 15in howitzers and guns were spread all along the front in any hotly disputed area. Big guns capable of high-angle fire were the only way to reach these underground targets; this is to say nothing of the long range of the big guns which enabled them to reach logistical and support targets behind the enemy lines (courtesy of the new phenomenon of aerial artillery observation). I would wager that there were probably as many personnel serving in the artillery arm as were serving in the infantry.

What then was the value of light (3in) rapid-fire field artillery? No infantry advancing in the open could survive against its observed fire. I have a wonderfully interesting analytical essay written shortly after WW1 by Conrad Llanza (MIT professor and US Army Colonel) who worked out statistics of artillery effects on the WEstern Front. Balck also touches on this as well (to a somewhat less dense degree).

B

You have to adapt the rules to the period obviously. And the length of turn, etc. But I still go with heavies are effective against almost targets. Almost all of the time.

As generally e.g. as a Plt Ldr and Co Cdr, if I requested FA support and it was denied. Because all that was available was 8 inch and they were holding for a bigger/better target. I don't think that is the way it works. Albeit it I understand priority of fires. (BTW we never had pizza delivered by any means when in the field ! )

I would still argue that for wargaem purposes it is to[o] simplistic to put a heavy piece down as more effective in all situations, and that lighter pieces would be better against attacking/maneuvering troops as seen in WW1 and WW2 on the eastern front/western desert and many other places.

Then you would have to design the rules to reflect that if you think it is accurate. However, by making heavier FA, e.g. only being able to fire every other turn would be a basic and general way to fix that conundrum, I'd think ? Again based on how much detailed you want the rules to have. And what you want to reflect.

I would add CnC into your thinking. As comms and fire control became more sophisticated, the longer range of the big guns meant one battery of 155s could cover the same ground as multiple 105 batteries. Using less manpower and being cheaper to produce.

Very true … we have a commo roll to all Call For Fire activations.

Also Economy of Force is one of the Principles of War, as you alluded to in your post.

No infantry advancing in the open could survive against its observed fire.

Yes as I mentioned about Infantry [and even Armor] spending a lot of time moving from cover to cover. And avoiding fly objects on the battlefield. Trying to get something solid between themselves and the incoming fires.

At Kursk the heavy tanks drew heavy artillery. So much so the infantry couldn't stay with them. Everyone talks of combined arms. The way to uncombine them is to hit them with artillery and neutralize the infantry and drive it to ground.

Now figure out the chance a single 152mm round has of landing close enough to damage the underground bunker in a barrage. It does not need a direct hit.

A 25 sq. m crater would have a radius of 2.82 m. Assuming a 152mm shell hitting within 2.82m of the bunker knocks it out.
Working out the geometry we have the destruction zone of an additional 2.82 x 5 added for each side and another 25m for the 4 corners. So 81.41 sq. meters plus the 25 sq. meters of a direct hit on the bunker itself. Giving a 106.4 sq. m destruction footprint. Dividing by 10,000 is ~ 1% chance per shell per hectare.

Something similar can be done to knock out a tank except the effect on armor by a 152mm shell is about 1.5 meters and the vertical area of a direct hit has to be taken into account.

Today, any target requiring more dramatic measures than a 6in-8in artillery fire mission can conveniently place a call to tactical air support for a Domino's Pizza delivery of a laser-guided 2,000lb JDAM or some such flavor treat.

Be careful when ordering Domino's in the field, you might get connected to some really big flavors:

And then there are mortars…

How much of the move away post-WWII from the medium artillery is due to the fact that mortars are more effect against non-hardened targets?

The us manula on artillery notes its prime role is to Supress and fix in place. You can do that with Mortars or larger guns. What becomes apparent even in s wargame is that big Guns indeirect aren't going to do much to well prepared defences. IF its a direct or very near miss is required; thenhit it will do a lot of damage. However big guns don't carry lots of ammo. So direct hits are unlikly when in indirect mode.

Aldso I am told supression is to some extent bangs per minuute so a Mortar with a ROF of asy 12 ROM may be better than a 155 mm at around 2 to 4 ROM.

The US manaual on the Mortar platoon and the unrestricted Artillery effects maunual are good places to start on a study.

At Kursk the heavy tanks drew heavy artillery.

Yes, Heavy weapons draw heavy fire.

So much so the infantry couldn't stay with them. Everyone talks of combined arms. The way to uncombine them is to hit them with artillery and neutralize the infantry and drive it to ground.

Stripping away Armor's supporting infantry is a standard tactic … as it seems to work.

Be careful when ordering Domino's in the field, you might get connected to some really big flavors:

Whose going to pay for it ?!?!?!?

What becomes apparent even in s wargame is that big Guns indeirect aren't going to do much to well prepared defences. IF its a direct or very near miss is required; thenhit it will do a lot of damage.

I'd say today that is not the same situation. With better tech and all.

Of course we saw with e.g. battleship bombardment in WWII many well dug in deep German and IJF positions could take a lot of damage from the very heavy guns on those ships. And it became the Grunt's with tank support jobs to clear them out. But in many cases the heavy fires did suppress some of the enemy's fires. And if they got a direct hit it depends on how well the defensive positions are prepared.

ROF is important, but a 155 shell is going to do more damage then an 81 or even 4.2 inch mortar.

And yes resupply is always a consideration.

How much of the move away post-WWII from the medium artillery is due to the fact that mortars are more effect against non-hardened targets?

Considering that 120mm mortars hit as hard as 155mm guns, and 81mm mortars probably hit as hard as 105mm guns, you're probably right.

Much shorter range, of course.

Yes, mortars are best for immediate suppression because they work closely with the front line infantry (mostly light mortars) and on occasion can observe the enemy target directly (should qualify as direct fire). A team of two 60mm mortars already set up can have 10 rounds in the air within 15 seconds bracketing and impacting within 30 seconds. The FO can be in comm with a field phone to give immediate corrections.

At Khe Sanh, Russian 120mm mortar rounds could penetrate 3 feet of sandbags and pierced metal planking.

Wolfhag

Considering that 120mm mortars hit as hard as 155mm guns, and 81mm mortars probably hit as hard as 105mm guns, you're probably right.

What does it mean to hit as hard?

Considering that 120mm mortars hit as hard as 155mm guns, and 81mm mortars probably hit as hard as 105mm guns, you're probably right.

Much shorter range, of course.

Also the range of infantry mortars has increased significantly since WWII. IIRC some 120 mm mortars these days have ranges over 10 km – comparable to many WWII divisional artillery pieces.

What does it mean to hit as hard?

He is probably referring to the amount of HE filling per round.

A 155 needs to have an observer on the actual target (not the area), be that direct LOS or through an observer. However even than at about 0.5% of range it needs a lot of shells to get a direct hit on small hardened target like say and Artillery Proof Bunker link or be very close.

Also the range of infantry mortars has increased significantly since WWII.

Yes as I and others have said tech has increase since WWII, etc. Including spotting, commo, lethality, etc. Note in about '85 the US ARMY took the 81mm mortars from their Infantry Co. TO&Es. But still keeping the 4.2 as a Battalion asset. For a number of reasons in all cases. Including the ability to call in other assets more efficiently and effectively. Plus again the increased lethality.

needs to have an observer on the actual target (not the area), be that direct LOS or through an observer.

All Indirect Fire needs an FO of some type if trying to get a direct hit on a point target, e.g. a hardened bunker. Or just an area target, e.g. Infantry and/or tanks dispersed in an area. Unless it is preplanned or H&I fires, etc.*

But with better i.e. optics, drones, etc., it is still much easier to hit what you want to more accurately then ever before. Along with being more accurate it limits collateral damage. And you hit what you are aiming at. E.g. one structure not the entire city block/grid square.

WWI, WII, etc. that was not the case generally. A grid square in many cases was close enough many times.

*E.g. if anyone has not seen the movie "A Bridge Too Far". Check out the scenes when the tanks and APCs of the UK's 30 Corps had a rolling FA barrage moving in front of their lead elements as they advanced. The barrage hit some concealed/hidden German AT Guns in a forest/treeline along 30 Corp's axis of advance. And took out/suppressed some of the AT guns. That is the way the tactic it is designed to work. The fire was indirect on preplanned targets.

Considering that 120mm mortars hit as hard as 155mm guns, and 81mm mortars probably hit as hard as 105mm guns, you're probably right.

What does it mean to hit as hard?

He is probably referring to the amount of HE filling per round.

My impression is that a 120mm Mortar may have as much HE filling, but hitting "as hard" will be entirely based on what you are hitting (or trying to hit).

Mortars are blessed with very high arcs, and so have near-vertical impact. They also have relatively low velocities. Low at the impact end, but also low at the firing end. At the impact end the result is a better distribution of blast effect and fragmentation, but a more shallow and less wide crater. At the firing end it means the walls can be thinner, meaning more HE content for the caliber, and more small fragments from the thin walls.

I have read first hand accounts, seen tech specs, and seen (first hand and in news accounts) the impact locations of mortar rounds -- they make small shallow craters with wide blast/skim markings. Howitzer and gun rounds make holes. Deep, wide holes.

This makes mortars more effective than guns of comparable caliber against soft targets in the open. But it also makes them less effective against hard targets or tug-in targets than guns of comparable caliber.

A 4.2in mortar round landing on a road is likely to slice and dice the infantry and soft transport on that road better than a 105mm Howitzer round.

If it lands next to your gun pit it is also more likely to mash up your 1-layer thick sandbag protection (and you, behind the sandbags).

A 4.2inch mortar round landing next to a tank is not likely to do as much damage as a 105mm Howitzer round. Nor is it likely to do as much harm to a fully underground dugout, or even a trench line.

All just impressions from my studies. Never threw either downrange, nor had them thrown at me.

-Mark
(aka: Mk 1)

More HE filling than the similar-caliber gun shell, more small fragments instead of big chunks/splinters, and better distribution of them.

More HE filling than the similar-caliber gun shell, more small fragments instead of big chunks/splinters, and better distribution of them.

One reason for the greater amount of mortar fragments is that the mortar bomb shell was iron and not steel. Steel is needed for shells of high pressure guns but not mortars. The Germans copied the Soviet 120mm mortar but their first batch of shells were steel. They produced less fragmentation. This was changed soon after.

The larger shells also have more room for specialized sub-munitions.

The arced trajectory of mortars [and howitzers] gives you the additional capabilities of hitting the tops of AFVs. Where the armor is generally thinner. However, it may be fairly challenging to hit that location. Better a direct fire weapon with AP rounds is generally preferred for "tank busting".

But as we know, HE rounds from mortars, FA, etc., will do a lot of damage to Infantrymen at the wrong place, at the wrong time. I was Rifle PL and 81mm PL in the 101. So I have a working knowledge of mortars, Inf AT wpns, etc., etc. In my long passed youth, '80-'82.

Overall you have a better chance of hitting a tank with a shell than a mortar. The difference is a shell which impacts on a tank has a higher chance of hitting a side or rear/front part. This is at 30 degrees impact angle is almost half the area of the top of a tank. There is a downside bit though as the height shields the far side of the tank from near miss effects. I'm in the process of writing a program that calculates the chances for a number of angles and tank sizes.

You don't need a direct hit: imgur.com/gallery/gIjCo

link

I think 15-20mm of armor was enough to protect against direct hits from 81mm mortar rounds. I recall something about the British Cromwell(?) being immune to direct hits by 25lb HE and would be able to drive through a barrage without critical damage.

Near misses that strip away a tanks camo will force it to fall back. Each time you force a Tiger or Panther (or most other tanks) to turn around and move there is a slight chance of a breakdown or bog.

Wolfhag

I know you don't need a direct hit. It would be good to know what was hit. Deck, side or near side. I had to write a program to find the exposed area of various tanks. And you can check it out. download.
link

I think 15-20mm of armor was enough to protect against direct hits from 81mm mortar rounds. I recall something about the British Cromwell(?) being immune to direct hits by 25lb HE and would be able to drive through a barrage without critical damage.

Churchill, IIRC, but they lost all their antennas and external stowage.

Not directly about battlefield effectiveness of artillery, but one reason for the continued popularity of the smaller caliber artillery pieces in the interwar years (besides budgetary restrictions on upgrading armaments) is the ease of transportation.

Back in the 30's, the level of mechanisation was still limited and artillery was towed either by horses or such tractors as were available, with self-propelled artillery at best at prototype level. Under such conditions the weight of the artillery pieces was an important factor in actually getting them to the battlefield in the first place, and as the caliber and range of the pieces increases so does the weight; a British 5.5 inch medium piece had thrice the weight of a 25 pounder.

The employment of tracked self-propelled artillery pieces by some of the combatants during WWII demonstrated a significant increase in (cross-country) mobility over towed artillery. Since then even heavier pieces have been mounted on self-propelled chassis.

Overall you have a better chance of hitting a tank with a shell than a mortar.

You mean from a direct fire flat trajectory round than arced from a mortar or howitzer …

You don't need a direct hit

Very true and yes you can do some damage to an AFV within out a direct hit. But chances of a KO is slim generally.

Near misses that strip away a tanks camo will force it to fall back. Each time you force a Tiger or Panther (or most other tanks) to turn around and move there is a slight chance of a breakdown or bog.

Agreed … Like firing at an aircraft with ground fire. If you get him to "jinx" to avoid being hit. His ordinance may miss or he may abort all together. You may not generally have to shoot him down to survive an attack.

Since then even heavier pieces have been mounted on self-propelled chassis.

Yes very few FA pieces today are towed. Save for some lighter Infantry type units, e.g. Airborne, Air Assault, etc.