So what's 4.5 inch Artillery? And other Arty queries...

[CombinedArms]

Allies (American only?) have the option of purchasing 4.5 inch artillery and I've recently run across a few references to it in Charles MacDonald's excellent A Time for Trumpets: The Untold Story of the Battle of the Bulge.

I'm familiar with the American 105 mm howitzer, which was a very standard artillery piece. This one seems just slightly larger (about 110mm). Can anyone explain what the difference is--and why there'd be this separate non-standard sized piece? Could it actually be a mortar?

Also, what were 4.2 chemical mortars--which MacDonald refers to several times?

While we're on the subject of US arty, I understand that the US 90mm antiarcraft gun was not used as an antitank gun--but the US would seem to need a big antitank gun even more than the Germans and after D-Day their need for AAA steadily declined. So why wasn't the 90mm used in a towed AT role? Was it unable to depress to AT levels? IF so, couldn't this have been modified?

According to MacDonald tungsten (sabot) rounds were rare in Dec '44 for US 57mm AT, but Brits had them. Any comments.

OK, one more question....How common was the 8 inch gun? Did it's availability increase later in the war? Anyone use this much in CM?

PS. Tried to search these questions but as usual lately got nowhere. Has anyone queried BTS about this and have they responded?

[ 05-07-2001: Message edited by: CombinedArms ]

[Ellros]

The 4.2" mortars were originally meant to be used to fire smoke shells, and I think CS gas (perhaps more knowledgable peoplec an add to that), but it turned out that they had a very effective HE round as well.

The 90mm AT gun was on a carriage vaguely similar to the German 88 Flak in that it took time to emplace, so was not as effective unless there was time to prepare a defensive position. It was used in this role in certain cases (Bulge comes to mind).

The 8" artillery was division level I think, so not quite as common as the lower sizes? I'm sure others know more on that than I do. I love to use them in CM, but the point cost and low number of shells usually restricts it to larger battles for me.

[Stalins Organ]

The Brits should certainly have 4.5" artillery, since they had a 4.5" gun - it looked pretty much the same as a 5.5" gun, and used the same carriage. Apparntly it wasn't much use tho', as the shell had only a small HE charge, so it was used for counter-battery work mostly.

I don't recall the US having anything in the 4.5" class??

The 90mm AA gun was unsuitable for AT work - it was tall, heavy, did not have suitable sights and wasn't needed since the allies were mostly attacking and heavy AT is most useful on the defence.

The M36 Jackson with it's 90mm was in pretty common usage by the end of the war.

Tungsten ammo was always in short supply, but the British seem to have made it a higher priority than other nations. they used APDS whereas others used HVAP type ammo.

The 4.2" mortars used by US and UK were originally intended as a method of attacking with chemicals - gas and smoke. Most nations had similar sized mortars for the same job, and also designated them "chemical" or similar. Of course chemicals were not used in WW2, so they reverted to using HE in a traditional artillery role.

dunno about the 8" sorry.

[ 05-07-2001: Message edited by: Mike the bike ]

[Scott B]

4.5 inch is 114mm -- pretty decent artillery piece in Combat Mission, midway between the 105mm and 155mm in blast rating. Pretty sure every allied army has these, though, not just the Americans. In fact, I'm pretty sure they're more common to the Brit based forces than the US... far as I know, we'd basically standardized to 105mm and 155mm by '44, upgunning from the old 75mm and 105mm mix.

4.2" chemical mortars are the old 107mm mortars... inferior to the German 120mm mortar. "Chemical" mortar may refer to smoke rounds or actual chemical munitions, although I'm inclined to think it's primarily the former.

8" guns and howitzers were employed at corps level. The typical mix at US division level (IIRC-- always some variance when you talk TO&Es and different time periods) was 3 battalions of 105mm and 1 battalion of 155mm, such that each maneuver regiment had a 105mm battalion in direct support, and the Division still kept a 155mm battalion in general support.

Scott B.

[Matthew_Ridgeway]

4.5” is an “odd” class relative to US ARMY field artillery. US ARMY WWII artillery was primarily made up of:

75mm

105mm

155mm

The 75mm was however somewhat restricted in use to light infantry units and parachute divisions. The 105mm was the US ARMY WWII workhorse, with most US infantry and armored divisions having 2 organic medium battalions of 105mm howitzers. US divisional artillery was typically rounded out with an organic heavy battalion of 155mm’s.

Commonwealth Classes:

3.45” (25-pdr) equates to approximately 87mm

4.5” equates to approximately 114mm

5.5” equated to approximately 140mm

I think the 25-pdr was sort of the Commonwealth workhorse. I am assuming that the 25-pdr kind of fit the role the US ARMY 105mm was filling. I don’t know what the typical organic layout of artillery for Commonwealth divisions was. Presumably, as with most of the major belligerents, there were two medium battalions and one hvy. battalion. Did the 5.5” fill the role in hvy. artillery battalions…or was that role filled by either the 4.5” or 5.5” depending on equipment availability?

[JasonC]

"Allies (American only?) have the option of purchasing 4.5 inch artillery"

The British have them too. It is a 114mm gun, and was a product of interwar cooperation between the UK and the US. The Brits designed the gun-tube and shell, while the US supplied the gun carriage design - the same as the 155mm howitzer (itself orginally a French design, incidentally).

"I'm familiar with the American 105 mm howitzer, which was a very standard artillery piece."

Correct. The 105mm howitzer was the standard divisional artillery piece, 36 of them in 3 battalions for infantry divisions, 54 of them in 3 battalions (6-gun batteries), self-propelled, in the armor divisions. The infantry divisions also had 6 shorter-ranged 105mm pack howitzers for each infantry regiment, 18 more all told. So both types of divisions had 54 105mm artillery pieces.

Incidentally, 1 battalion of 12 155mm howitzers was also standard equipment for the infantry divisions.

"This one seems just slightly larger (about 110mm)."

114mm actually.

"Can anyone explain what the difference is--and why there'd be this separate non-standard sized piece? Could it actually be a mortar?"

It is not a mortar. It is a *gun* rather than a *howitzer*. A much longer ranged, higher velocity piece, with a longer barrel. It is more like the size of a 155mm howitzer, but with a relatively small bore diameter. It is meant to be a superior weapon for counterbattery fire in particular, using its longer "reach" to hit enemy gun positions far in the enemy rear.

It was used in non-divisional, heavier field artillery units. Corps and army level artillery. I will explain a bit more about how those were organized and how common they were later on. But just as a first approximation, they were a lighter substitute for 155mm *guns* (not howitzers).

US field artillery groups above the division level mixed howitzers with guns, generally around 2 battalions of the former to 1 battalion of the later. The idea was that the gun portion provided reach into the German rear, artillery positions, transport bottlenecks, etc, while the howitzers needed only to reach the front line or near it, most of the time. More on higher level US artillery practices, below.

"what were 4.2 chemical mortars?"

These were heavy mortars intended for chemical warfare, gas warfare, should it break out. I.e. if the Germans used gas, they would be the primary or initial means of replying in kind with poison gas shells. In the absence of chemical warfare, they were optimised to perform smoke missions, both ordinary smoke and white phosphorous.

Originally there was no HE shell for them, but an artillery officer assign to them developed one independently in late 1942. From 1943 on, they were therefore able to provide HE support to the infantry as well as smoke missions.

There were 16 "battalions" of them serving in the ETO, plus 2 in Italy and 6 in the Pacific. These battalions were bigger than standard artillery battalions because they used the infantry, mortar structure and unit size names. That is, 4 mortars were a "platoon", and 12 a "company", instead of those being called batteries and battalions as the same number of tubes would be called in the field artillery. Ordinary practice was to assign 1 company of them (12 mortars) to each infantry division.

"the US 90mm antiarcraft gun was not used as an antitank gun"

Well, it was occasionally in a pinch. I've read some after action reports that recount them KOing Panthers. But it was not a standard practice.

"why wasn't the 90mm used in a towed AT role?"

Just bad doctrine. The men were not trained for it, the gun did not have the best sight for it equipped, 90mm AP was not normally supplied to the AAA, the units were usually kept at army level and above scanning the sky for German planes. A variant of the same gun was mounted on the Jackson tank destroyer and did excellent work, but the towed AA themselves were not pressed into the ground-combat role on any systematic basis.

But in the Battle of the Bulge, the Germans got far enough into the rear areas to run over some of them. And then they were used as anti-tank guns, because they were available and anything that could kill a tank was worth its weight in gold. But this seems to have been a purely ad-hoc measure by local troops, not anything the chain of command planned or approved. They worked quite well by the way, so it was obviously a mistake not to have gotten more work out of them.

"According to MacDonald tungsten (sabot) rounds were rare in Dec '44 for US 57mm AT, but Brits had them. Any comments."

I don't have direct knowledge of that one way or another. The 57mm was the standard AT piece in the infantry for both, at the battalion and regimental levels. Both used heavier, 76mm guns at the divisional level. The Brits had used the 57mm - the 6 lber in their terms - in a number of tank designs, too, while the U.S. never did. Valentines and Churchills with 6-lb guns were built, for example. It may be that they devoted more tungsten to producing 6-lb "T" rounds because of this. Those tank models were obsolete in 1944, but the ammo may have lasted. The US was concentrating available tungsten on 76mm T rounds, which could deal with Panthers and Tigers, and not making enough.

"How common was the 8 inch gun?"

I suspect that the question conceals a misunderstanding. You probably mean, "any 8" artillery piece" and "in US service". "Gun" is a term distinct from "howitzer", but is often used generically as well, for both types. As I use it too, of course, sometimes. The 8" *gun*, proper, was quite rare. But the 8" *howitzer* was reasonably common, though less common than 155mm howitzers.

While the US artillery at the division level and below is usually pretty well known - on this board I mean - the use at higher echelons is often underrated. The US had a substantial amount of corps and higher level artillery. In fact, there was about an artillery brigade's worth of guns above the division level, for every division, roughly doubling the total number of tubes available. And the higher level tubes were heavier than the division level ones.

First the top level guns to get those out of the way, because they are rare enough to matter little. 8" guns (proper) were used side by side with 240mm howitzers, as the longer-reaching part of that heaviest mix. These heaviest guns were different from others, in that a battalion comprised only 6 guns, not 12. The U.S. had 15 "battalions" of the 240mm howitzer, with 5 "battalions" of the 8" guns. Organizationally, that would typically mean 5 "heavy" artillery -groups-, as they were called, each with 24 pieces, 6 8" guns for counterbattery range, 18 240mm howitzers for pulverizing strongpoints. Not very many of these things, they are special purpose items really.

The bulk of the higher level artillery was organized into brigade sized formations. Sometimes doubled up into 6 battalions, sometimes reduced to 2, but generally 3 battalions with 1 long ranged gun and 2 shorter ranged howitzer. And here we are talking substantial numbers - a 3-battalion artillery group for every division.

The pairings were of two general types. The lighter pairing would have 155mm howitzers, two battalions, paired with either 4.5" guns or 155mm guns, one battalion. About half of them had the 4.5" guns, half at this level or pairing type, the 155mm guns. This level or pairing type (155mm howitzer "base"), comprised about 2/3rds of the heavy artillery. The other 1/3rd had 8" howitzers as the base type. 2 battalions of those, paired with 1 battalion of 155mm guns.

So, overall result is 1/3rd have 2x155mm howitzer plus 1x4.5" gun, the next 1/3rd have 2x155mm howitzer plus 1x155mm gun, the last 1/3rd have 2x8" howitzer plus 1x155 gun. In all cases, battalions, so in CM module terms those amounts multiplied by 3. Naturally, they mixed and matched and swapped sometimes, so the structure would not be perfect, but that is the basic plan or force mix.

In addition to all of the above, there were some lighter battalions at the corps level with additional 105mm. Most of the 105mm were at the division level, but there was, on average, about 1 extra battalion per division, at higher levels. Which could be reassigned in 2-6 battalion groupings, to double the vanilla 105mm support a given division could get, when needed.

How common does that mean 8" support ought to be? Well, it means a typical corps had 8" support somewhere. When heavy artillery support from corps level and above is available, you'd expect 4.5" (the low end) 1/9th of the time about, and 8" support another 2/9ths of the time. Most of the time, 6/9ths, it would be 155mm.

Since there were also 155mm howitzers at the infantry division level, that type would be even more common. If you want it in die roll terms, when there is heavy artillery support, roll 2d6. On a roll of 2-3, you get 4.5". On a roll of 10-12, you get 8". The rest you get 155mm. (6/36 155 gun, 20/26 155mm howitzer).

I hope this helps, and that was a fine set of questions by the way.

Correction made, I flubbed some of the chances first time around - sorry.

[ 05-07-2001: Message edited by: JasonC ]

[Ts9]

Everything you ever wanted to know about the 4.2" chemical mortar but were afraid to ask:

www.4point2.org

[JasonC]

At one point I said "pretty well none", when I meant of course "pretty well known". One of those misfirings upstairs between mind and fingers - LOL. Sorry for any confusion.

[offtaskagain]

<BLOCKQUOTE>quote:</font><HR>Originally posted by CombinedArms:

While we're on the subject of US arty, I understand that the US 90mm antiarcraft gun was not used as an antitank gun--but the US would seem to need a big antitank gun even more than the Germans and after D-Day their need for AAA steadily declined. So why wasn't the 90mm used in a towed AT role? Was it unable to depress to AT levels? IF so, couldn't this have been modified?

[ 05-07-2001: Message edited by: CombinedArms ]<HR></BLOCKQUOTE>

The 90mm AA was indeed modified for AT use. The new variant was called the M2 I believe. It was mounted on a new carriage that allowed it to depress below horizontal and be unloaded faster.

[Stalins Organ]

Can anyone confirm a 4.5" gun in US service? I've never seen any reference otehr than as an experimental pice on the chassis that eventualy became the M41 155mm SP howitzer.

and the Brit 4.5 was NOT a joint development with the US - it was a replacement for the 60 pdr (127mm) and initially produced on the 60 pdr carriage as the 4.5" Mk 1 - 30+ of these went to France in 1940.

The Mk 2 used the split-trail-vertical-recuperator ccarriage later used for the 5.5" gun/howitzer, and NOT the carriage of the US 155mm.

There were no other 4.5" guns in British service AFAIK, although a number of 4.5" howitzers of WW1 vintage were still in use up to at least 1942 on modernised carriages.

[offtaskagain]

I believe 4.5s were in U.S. service in Italy. I know they weren't declared obsolete until the day the war ended. We should ask someone from Talonsoft, as they gave the U.S. 4.5s for West Front.

[JasonC]

The following US artillery battalions used the 4.5" gun.

172nd, 176th, 198th, 211th, 215th, 259th, 770th, 771st, 772nd, 773rd, 774th, 775th, 777th Colored, 935th, 939th, 941st, and 959th.

It was the US ones that used the US gun carriage, and the British designed tube and shell. Here is a source's discussion of the subject -

"A companion of the 155mm howitzer was the 4.5" gun (an indigenous 120mm gun was one of the few failures of the inter-war design projects). The tube of this gun was of British design, while the carriage was that of the 155mm howitzer (carriage commonality between companion guns and howitzers was one of the hallmarks of U.S. artillery designs)."

So, they used the 155 howitzer carriage, and because the 120mm gun the US army tried to develop in the interwar years was regarded as a failure, they put the British 4.5" gun tube on it.

[Matthew_Ridgeway]

I reckon this is a waste of my time, but for posterity sack...From “Mr. Artillery” Ian Hogg regarding the 4.5 inch gun.

<BLOCKQUOTE>quote:</font><HR>Britain's inter-war mediums were

the 6-inch gun, the 6-inch howitzer

and the 5-inch 'sixty-pounder'. These

were all of First World War design,

and in spite of modernisation in the

form of pneumatic tires, mechanical

draught and improved ammunition,

were all a little long- in the tooth and

cumbersome to boot. In spite of this,

they served valiantly through the

early part of the Second World War,

their last major campaign being in

Eritrea in 1941.

In the mid-thirties a specification

had been issued by the British General

Staff calling for a 5-inch gun to weigh

five and a half tons, fire a shell of

ninety to a hundred pounds to a range

of 16,000 yards. After much chopping

and changing, this evolved, in the

spring of 1939, into a 5.5-inch gun, and

in August of that year the design was

approved for manufacture.

Before this, though, the demand for

a medium gun of long range and with

a modern shell had become pressing,

and, as an interim measure, seventy-

six old sixty-pounders were fitted with

4.5-inch barrels in 1937. On trials they

achieved a range of well over 20,000

yards and were introduced into service

in late 1938. At the same time the

Director of Artillery personally urged

that a design of 4.5-inch barrel should

be produced which would fit onto the

carriage then being designed for the

new 5.5-inch gun. The proposal was

accepted, but difiiculties in carriage

production held up both weapons,

which finally got into service in

quantity in the early days of 1941;

the first 5.5s to see service were fired

in Gyrenaica in 1942.

The 4.5 gun was partnered with the

5.5 in Medium Regiments BA and

acted as the long-range sniper of the

unit, although they were never as

popular as the 5.5 due to the lighter

shell (551bs as opposed to the 5.5

gun's 100 Ibs ).

The US experience in the field gun

line during the First World War was

repeated in the medium gun line as.

well; the French 155rnm. gun. and how-

itzer were adopted, and remained in

service after the war ended. The

155mm howitzer M1918 was the Ameri-

can-manufactured version of the ori-

ginal French design by Schneider.

During the 1920s and 1930s it had been

brought up to date by the addition of

pneumatic tires and adapted for high-

speed lowing. It was basically a two-

wheeled box trail type with shield,

using a short and heavy barrel on a

long cradle, and using bag charges

with the original French breech

mechanism.. In 1939 it was superseded

by a completely new design, issues of

which began early in 1942; this was the

155mm howitzer MI, a modern two-

wheel, split-trail affair, with the gun

Itself having a longer barrel, more

modern screw breech mechanism,

and slung in a ring-type cradle. Large

spring balancing gear formed a pro-

minent feature of this gun. It gained

a splendid reputation' for accuracy,

and I have personally seen many

displays of fine shooting with these

weapons during- the Korean War.

During- the summer months of 1944,

development beg-an on a self-propelled

version, the T64BI, which entered

service in 1945 as the M41.

During- 1939, when the redesig-n of

the 155mm howitzer was proposed, it

was thought that a 4.7-inch (120mm)

g-un could also be produced as a

partner piece on the same carriage,

to give a greater rang-e. A simpler

solution was accepted, namely the

adoption of the British 4.5-inch gun

barrel slipped into the MI howitzer

cradle, and using the howitzer breech.

This gave 21,125 yards with the British

55 lb shell, and also g-ave a valuable

interchang-eability of ammunition

between US and British forces, but the

US Army felt that the shell was too

weak, having- a filling- of only 4.5 Ibs

of TNT. This was due to the British

desig-n practice of using- cheap low-

grade steel for shell bodies, thus

dema:a.ding• thicker metal walls and

leaving- less room for the high explos-

ive filling•. American practice, based

on an easier supply of higher grade

steel during war, was to make shells

with larger cavities to get greater

explosive content and more lethality.

In view of this poor shell performance

the US 4.5-inch gun MI was declared

obsolete on the day after hostilities

ended in Europe.

The 155mm gun M1917 was original-

ly the French 155mm '&PF' (Grand

Puissance, Fiuoux) taken over by the

AEF in 1917. The M1918AI was the

American-made version. The car-

riages had been modernised over the

years, and in 1939 the gun was in

service on the M2 or M3 carriage, split

trail pattern with pneumatic wheels.

As well as forming the equipment of

field units, these guns were also widely

employed by Coast Defense Artillery,

since they were ideal for rapid deploy-

ment along the coastline. Positions

were prepared in advance with con-

crete emplacements called 'Panama

Mounts' (from their place of origin)

which consisted of a central platform

on which the gun wheels rested and a

circular track about which the trails

could slide to give rapid traverse over

large angles.<HR></BLOCKQUOTE>

[IPA]

An example of a British unit using 4.5" guns, was the 64th Medium Regiment RA during Operation Market Garden. This unit was largely responsible for the XXX Corps Artillery support provided to the 1st Airborne Division at Arnhem, performing shoots at extreme ranges from as far away as Nijmegen. From memory, the unit comprised 1 battery of 8 no 5.5" and 1 battery of 8 no 4.5" guns (each battery divided into two troops of 4 guns). I have no idea whether or not they were using WWI guns with modified carriages, but can provide a photograph if anyone's interested.

Peter

[JasonC]

"I reckon this is a waste of my time"

LOL. Well, it was certainly interesting to me. I tracked down some additional "evidence" of US use of the 4.5" gun, in case anyone wants any.

1. the capsule discussion of the Elsenborn ridge affair in the US field artillery association's "history of the field artillery", says the battalions firing behind Elsenborn were 4x105mm howitzer, 6x155mm howitzer, 2x155mm gun, and 1x4.5" gun.

2. This passage from the US official history of the Bulge - "An attempt to give greater weight to the artillery in the St. Vith-Vielsalm area failed when the 4.5-inch guns of the 770th Field Artillery Battalion were cut off at Samree en route from La Roche."

3. The following list of attachments to the 101st Airborne during the Bulge fighting contains 2 field artillery battalions specified as armed with 4.5" guns - one of them the same as the preceeding, the 770th.

"Two platoons, Co. B, 796th AAA (AW) Battalion, 9-10 January.

Batteries A, B, & C, 61st Airborne AA Battalion, 11-18 January.

2d Tank Battalion, 19-30 December.

Combat Command R, 9th Armored Division, 20-31 December.

Combat Command B, 10th Armored Division, 20 December-18 January.

Combat Command B, 4th Armored Division, 8-10 January.

755th Field Artillery Battalion (155 How.), 19 December- 12 January.

969th Field Artillery Battalion (155 How.), 19 December- 15 January.

775th Field Artillery Battalion (4.5" Gun), 19 December- 15 January.

333d Field Artillery Group, 20-28 December.

559th Field Artillery Battalion (155 Gun), 1-3 January, 11-12 February.

687th Field Artillery Battalion (105-How.), 12-18 January.

770th Field Artillery Battalion (4.5" Gun), 13-14 January.

193d Glider Infantry, 3-7 January, 14-18 January.

705th TD Battalion, 20 December-18 January.

Co. B, 811th TD Battalion, 3-11 January.

Co. C, 704th TD Battalion, 4-6 January.

Co. A, 602d TD Battalion, 4-6 January.

611th TD Battalion, 6-7 January.

Co. B, 704th TD Battalion, 9-11 January.

Co. C, 609th TD Battalion, 11-12 January."

4. I found a biography of one member of the 172nd field artillery on the web. It contains a line stating they turned down an offer of 155s in favor of keeping their 4.5" guns, while still in England before D-Day. Here is the URL of the bio (most of it unrelated, but might interest somebody) -

http://members.aol.com/famjustin/Gieskebio1.html

And the same site has a log of all the days of shooting, rounds expended, moves, etc of the battery in the whole war. For those trying to get a sense of what a higher level battery did, how often if was firing and in quantity, at what sort of targets, etc, an interesting lump of data. Not exactly riveting reading, since most days they shot at things but nothing much else happened, but if you want to know what 4.5" guns fired at, there it is. Here is that URL -

http://members.aol.com/famjustin/172FAlog.html

I think it is pretty darn well established...

[Stalin's Organ]

Thanks Jason & Mathew - I don't think you're wasting your time

Stalin (also Mike the Bike)

[Redwolf]

Fine thread. More questions:

Why is the U.S. 4.5 inch FO modeled to be faster than the British one, everything else equal except price? Did the British use an inferiour carriage for the same tube?

In CMBO, the on-map 25pdr is much faster to set up than the 105mm howitzer, is that correct?

From the other artillery thread currently running: What is the difference between British and U.S. 4.2" mtr?

[Kanonier Reichmann]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JasonC:

At one point I said "pretty well none", when I meant of course "pretty well known". One of those misfirings upstairs between mind and fingers - LOL. Sorry for any confusion.<HR></BLOCKQUOTE>

Ooooh... black mark against your name Jason. How dare you make a mistake!

Regards

Jim R.

[CombinedArms]

My thanks to all, and especially Jason (!), Mike tb, & Matt R for for your incredibly informative responses to my various questions. I now understand all of these issues much better than I did.

I'm glad several of you are finding this an interesting thread. Here are a few further questions that arise from what's been written:

Someone said that armored divisions used SP105s instead of towed. Would these be "Priests"? (I know that this is the British term, but also used by Americans and is the CM). The armored divisions also used SP 155s. Were either of these units likely to appear outside of armored divisions? How often were they used as Priests most often are in CM, as direct fire assault guns? I love 'em for knocking down buildings.

Some complain that in CM Priests can't be used for indirect fire. Could they have be used for indirect fire in real life at typical CM ranges? That is, can you indirect-fire a Priest gun at 1000-2000mm?

Also, I'm curious about 105 pack howitzers. Could these be broken down and moved in a truck (or jeep or pack mule?) as well as towed? IF so, how frequently did this happen in the ETO? (I assume it was often essential in the Pacific, where I think 75mm pack howitzers were common.)

In general, Jason and others have indicated what an impressive amount of artillery US units often had to support them. I've been reading MacDonald's book on the Battle of the Bulge and find descriptions of artillery use to defend the villages south of Elsenborn ridge to be most fascinating. He makes clear how with effective use of artillery and attached tank and TD battalions, a US infantry division could improvise defensive positions on the fly--either falling back on them or hurrying into them after pulling out of an attack-- and defeat one or more Panzer divisions with supporting infantry. From MacDonald's account Gen. Robertson of the 2nd Div. was the real mastermind of the Elsenborn defense, commanding his own division plus much of the comparatively raw 99th, which had been forced into retreat by the German attack, and shaping them into a coherent defense that made full use of the artillery backing. Other units filled in around their timely defense of key points.

It's also clear that a fully reinforced inf division (with that tank and TD battalion and its share--or more, if heavily engaged--of corps level arty) could be a formidible fighting force. But not all commanders used their resources as cleverly as Robertson did. Cota (a D-Day hero) for example, with the 28th division to the south, seems to have had a far less skillful feel for the flow of battle.