75MM Pack Howitzer

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fitz RE:75MM Pack Howitzer 6/1/2005 9:46:16 PM

It was popular enough, surviving in 3rd world armies at least into the 1980's as the M-116 (IIRC).

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neutralizer RE:75MM Pack Howitzer 6/2/2005 6:00:39 AM

Accuracy is not an inherent attribute of a gun (artillery type that is). Accuracy is basically a measure of the ballistic data, ballistic model, and the applications of the corrections for non-standard condition, ie wind, temperature, barrel wear. And of survey. Not forgetting the accuracy with which the target was located. The innate (not strictly true, it increases with wear) characteristic of a particular type of gun is dispersion (otherwise called consistency), this measures the spread of the fall of shot around the mean point of impact (which may or may not be near the target, that's accuracy). For guns this is a probable error in line and a PE in range. It is not a CEP, and while the 2 PEs can be mathematiclly converted to a CEP is in meaningless in practical terms because the 2 PEs are typically about an order of magnitude different. These PEs are given in the firing tables. They vary with range and charge.

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FSV RE:75MM Pack Howitzer 6/2/2005 6:26:35 AM

Gilbert: First we need to find out what type of 75mm Howitzer it is. 75mm Pack Howitzer = A M1 or M1A1 pack howitzer, mounted on a 75mm pack howitzer carriage M1 [has steel rimmed wooden wheels] or M1A1 [has tires, on steel rims & modified to be towed by a vehicle]. Both these carriages have an axle (left) traversing mechanism, and the trail is "modified box" (doesn't open up). 75mm field howitzer = A M1 or M1A1 pack howitzer, mounted on a 75mm field howitzer carriage M2A1, M3, or M3A1 (designed to be towed by vehicles). These carriages have a firing base and trails open from the 'traveling' position. The traversing mechanism for these carriages moves the gun cradle on the firing base. The 75mm Pack Howitzer was designed to be quickly broken down into 6 pack mule loads (plus 6 mules for ammo). There were 9 men to a gun crew (officially a Section). Here is some data; Shell HE, M48. Muzzle Velocity: Maximum = 1,250 ft per sec. Minimum = 700 ft per sec. Maximum Range = 9,489 yds. Elevation = +5 deg's to +45 deg's. (+9 deg to +49.5 deg f/ M2A1 & M3; +50 f/ M3A1 carriage) Traverse = left & right 3 deg's. (L&R 22.5 deg's f/ M2A1 - M3A1 carriage) Rate of Fire: Short burst = 6 rds per min. Prolonged firing = 3 rds per min. Weight in firing position = 1,269 lbs Weight with accessories = 1,487 lbs (Phillips pack saddles not included, 94.5 lbs each. The Marine Corps used the 75mm Pack Howitzer until the end of WW2. And kept them in storeage (each Arty. Reg. had a couple of them for crew training) until the mid '50's. I'm going to outline a very basic Table of Equipment (TE) for a WW2 Arty. Reg. in the Corps. 1 gun + crew = a section. 2 sections = A Plt. 3 Plt's = A Firing Battery (supports an infantry Bn.). 3 Batterys = a Bn. (supports an infantry Reg.). 3 Direct Support (75mm Pack Howitzer) Bn's & 1 General Support (105mm Howitzer) Bn. = a Reg. Larger caliber howitzers and guns were in independent Firing Batteries or Bn's and were attached to the Divisions as needed, by higher command. By the time of the Iwo Jima landing the TE had changed to the Direct Support Bn's were 105mm howitzers & the General Support Bn was 75mm Pack Howitzers. After the war the General Support Bn's were converted to 155mm Howitzers. The Marines loved the Pack 75, from the time thay got them in the '20's. It was simple, rugged, reliable and could go wherever they went. If mules were not available Marines could 'strong back' the howitzer (4 or 5 Marines per 1 mule load). For the M1 carriage there was also a Limber, light, M2 (22 rds) & a Caisson, Light, M1 (52 rds). The limbers could be configured to pulled by mules or Marines (in the Corps view, they were inter-changeable). A Section had 1 pack howitzer, 2 limbers & 1 caaisson. The M1A1 carriage was towed by the Dodge 3/4 ton PC. In 'tight' situations it could be towed by a jeep. [The 105mm howitzer required a Duce & Half.] The Pack 75 was the first artillery 'ashore' during the Amphib. landings. It was easly 'man handled' or (towed by jeep) out of the PC landing craft [the 105mm howitzer required the larger LVPC boats]. In '43, when the Corps started Offensive Assault & Seize Landings (The 'Cannel' was a Seize & Defend, with limited offensive clearing, operation for the Corps. It was the Army that later 'cleared' the island.) it was found that the Pack 75 lacked the HE power to 'take on' (destroy) the Japanese defensive positions. The '75' was great at killing troops in the 'open' & in fighting holes & its rds. could be brought in closer to friendly lines than the '105'. But the '105' was better at taking care of the 'bunkers' & 'covered' positions. Also the 'Pack 75' did not have an Illumination Round, which was a problem when it was realized that most Japanese attacks occured at night. The Corps then started converting its Direct Support Bn's. to 2 '75' Batteries & 1 '105' Battery per Arty.Bn. Then 1 '75' Battery & 2 '105' Batteries per Arty. Bn. Then to the TE listed above. It was found that the 81mm mortars at the infantry Bn. level could take over the 'close' fire support mission from the Pack 75's, when the Corps changed from 4 tubes to 6 tubes per motar plt., per inftary Bn. The Corps kept the '75's' because: 1. The 'Pack 75' was more accurate than the 81mm mortar, especially in windy conditions. 2. It had a greater range than the 81mm mortar (5,000+ yds) & a shorter 'time of flight' for a given range. 3. It could go where the '105's' couldn't. 4. In a surveyed position, it took only 3 minutes, to assemble from 'pack loads' and be emplace. 5. It could (& was) be used in the 'front lines' in the Direct Fire Mode. Many a Marine 'Cannon er' went got 'commde hugging' drunk, the day when the Corps retired the "Pack 75' from the inventory. It was a simple, reliable, flexable weapon, that 'got the job done'. You can go to link and get zerox copies of 'Pack 75' manuals. The FM 6-110, dtd 1940 gives the commands/drill for disassembly/assembly of the 'Pack 75'. This sight has all sorts of manuals, including foreign weapons. First payment has to be by check or Money Order, after the first order they will accept Credit Card payment. I hope this helps you. Any other questions, yoy can contact me at fsvjacobs@aol.com

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Gilbert RE:75MM Pack Howitzer 6/2/2005 10:58:14 AM

Gentlemen, Here are a few more details on the Howitzer. ------------------ Markings on Breech Ring 07967-8 HOW. 75MM. M2.M3. & PACK M1A1 ORD. DEPT. U.S.A. PA DRAPER CORP. NO. 9162 121 LBS. INSP. B.O.L. 2155-6915 ---------------- Tag Markings on Recoil Mechanism NO 2366 ACR MECHANISM, RECOIL 75MM PACK HOWITZER MIA. 7PA HANNIFIN MFG. CO. 19_ _ --------------------- Tag Markings on Carriage NO. 94 CARR. HOW., 75MM M1 ROCKISLAND ARSENAL NFR --------------------- The Carriage can be folded up. It has a blade at the end, apparently for digging into the soil to prevent the howitzer from rolling back, and it has a tow ring at the end.

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FSV RE:75MM Pack Howitzer 6/3/2005 7:25:04 PM

The carriage tag (M1) confirms that the complete weapon is a Pack Howitzer. If you google 75 MM Pack Howitzer you will find severial sights with information.

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Gilbert RE:75MM Pack Howitzer 6/7/2005 12:05:19 AM

Your comments are both interesting and helpful. Following up on the table of equipment data: How were these guns normally were deployed? The photos I've seen usually show the larger guns deployed en masse, and in a large scale assault, there could be as many as 10,000 guns all along a front firing into the target area. However, I usually see the smaller guns like the 75s in singular deployment often dug into a trench or tunnel. I figured that since the were small and portable, that's the way they were used -- possibly wheeled up to the front lines to be used against line-of-sight hard targets. Could you comment on this?

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Gilbert RE:75MM Pack Howitzer 6/7/2005 12:22:11 AM

I think I get the general idea about accuracy. CEP is out, and probable error is in. I've done a little reading and now know that there is, at least, a range PE and a Deflection PE. I think that based on these, the gunner can use a firing table or slide rule to predict the size of a rectangle on the ground in the target area that outlines the dispersion pattern where almost all of the rounds will fall. Apparently, even if none of the gun's settings (elevation or azimuth) are changed and the gun is well anchored, the rounds will be scattered in some random pattern within this rectangle. If I am mostly correct on this, a person with more knowledge than I should, by using the firing table, be able to calculate the size of that rectangle at various distances such as 1, 3, or 5 miles on a level terrain. Do any of you have this information or could any of you make a good estimate?

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neutralizer RE:75MM Pack Howitzer 6/7/2005 8:27:26 AM

I think talk of lining up 10,000 guns is a tad over the top. Even for the last couple of years of WW2 on the Eastern Front. Nothing on that scale on the wetern fronts in either WW, although it did reach the low thousands for army group level operations by the Germans in 1918 on a front of perhaps 50 miles. I pointed out this site link in connection to comms, it also explains PE, etc (Errors & Mistakes page), the intro stuff on arty is also useful. There were important differences in the detail of UK and Brit methods, organisation, etc, but for a broad picture all arty is fairly similar and Brits did use a few 75mm.

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FSV RE:75MM Pack Howitzer 6/7/2005 11:12:02 AM

Normally, the Pack Howitzers were emplaced as a battery, with a 20 to 50 meters distance between guns. The basic emplacement formation was "guns on line". imagine an upside-down T. The crossbar is the 'gun line' and the shank is the Primary Direction of Fire (PDF). Whenever possible, the crews put the gun in a 'firing pit', dug by the crew. The 'basic' pit was at least "muzzle" (gun at 0 deg. Elevation) deep. The 'firing' side was 1.5-to-2 times the the wheel base of the howitzer. The 'flank' sides were angled (20 deg) back to the 'base' side. This allows the crew to reposition the gun trail, to 'cover' a wide firing arc. I'm use to modern gunnery terms. Distance is measured in meters (m). Angles are expressed in mils. 360 deg's = 6,400 mils. 1 deg. = 17.777777 mils. 1 mil @ 1 km = 1 m, another words at a range of 1,000 m if you move your point-of-aim 1 mil, you move your point-of-aim 1 m in deflection (def)/azmuth (az)/ width (w) or elevation (elv)/height (h). At a range of 6.750 km (6,750 m) a 12.7 mil change = a change of 85.725 m in az. or elv. The 75mm Pack How. has a traverse of 47.5 mils (2.65 deg) left & right of 0 mils. So at its maximum range of 8,676 m (9,489 yd) the 'Pack 75' can deliver projectiles into an area 824.22 m wide, without having to reset the trail. The 'Pack 75' has an elv of -89 mil (5 deg) to +800 mil (45 deg). One full turn of the traversing wheel = 4.1 mil. One full turn of the elevation wheel = 24 mil. Knowing the last 2 bits of info allows rapid adjustments for firing gun/platoon/battery patterns. (I'll get into that later) Dispersion for artillery is given as a % X range (km), by firing charge. The gun is relayed (aimed) to the same aiming point (aiming stake) after the round is loaded, before firing. For the 'Pack 75' the deflection dispersion (at full/max 'charge') would be no more than 0.05% (0.5 m @ 1,000 m) left/right. And 0.5% (5 m @ 1,000 m) +/- in range. The dispersion % is different for each 'firing charge'. The 'deflection dispersion' % doesn't increase that much for lower charges, but the 'range dispersion' % increases considerably as the 'firing charge' is reduced. When the Battery moves in to its 'firing position', the guns are set in "parallel", ie the axis of the gun bores are parallel to the PDF (0 mil def). And the gun closest to the center of the "firing line" is designated as the "Base" gun (#3 gun for a 6 gun battery, or #2 gun for a 4 gun battery). When a Battery gets a Fire Mission, the battery Fire Direction Center (FDC) determines the 'charge', def & elv needed to hit the target and relays this information ("Fire Mission {after each gun 'talker' reports back "ready" to the FDC), HE, Charge 3, Super Quick, # of rounds, Deflection-Left 23.8, Elevation-Plus 632.5, Ready-Report") to the guns. After each gun reports back to the FDC "Up" (round configured, loaded, gun layed, ready-to-fire), the FDC will have the "base gun" fire. Working with the Forward Observer (FO) the FDC will adjust the def & elv of the 'base gun' (the other gun crews will apply the same data to their guns)until the projectiles land within the CEP. Then the entire battery will 'fire'. The FDC can set the 'battery's' impack pattern/shape & area/density as needed for best "target effect". This is done by specifing the firing pattern used by each gun (ie, "Killing Cross" or "X" pattern {1st rd center, a rd at each end of the pattern, 6th rd center} for example) and having different def & elv settings from the 'base gun' settings. I've got to go, but will add more later.

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Gilbert RE:75MM Pack Howitzer 6/7/2005 1:01:11 PM

The British Web page at link is very interesting and quite detailed. I see that they have a gun they call 25-PDR which is just a little larger than the U.S. 75MM, so there are probably some very close similarities where the British information might apply. Regarding the 10,000 guns: This is probably rare indeed, but I was actually trying to be conservative because I could hardly believe what I heard during a History Channel account of Zhukov's final assault on Berlin. The narrator stated that Soviet guns were lined up every 18 feet, basically wheel-to-wheel, for 50 miles. That would be considerably more than 10,000. For a short account of some of these eastern front battles, please take a look at: link Here is an excerpt: THE BATTLE OF BERLIN "Within the city were a million German defenders, three-quarters of which were regular army forces, with 1519 tanks, 9303 artillery guns and a few aircraft. In the heart of the city lay the Reich Chancellery, with Hitler and his General staff. Zhukov alone had at his disposal 14,600 guns, 3155 tanks and self-propelled guns, and 1531 rocket launchers. More than 2 million Soviet soldiers and 7500 aircraft took part in the assault on Berlin." Also about that same event from Cornelius Ryan's "The Last Battle," on page 348: "With an earsplitting, earthshaking roar the front erupted in flame. In a bombardment that had never been equaled on the eastern front, more than twenty thousand guns of all calibers poured a storm of fire onto the German positions."

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neutralizer RE:75MM Pack Howitzer 6/8/2005 5:48:18 AM

The definitive English language source on Soviet arty is 'Red God of War' by Chris Bellamy in 1986 (today a professor (proper type not jumped up lecturer) at a reputable university, former arty officer and intelligence staffer, fluent Russian speaker). The Sovs did have very high concentrations of guns in a breakthrough sector. The assault on Berlin involved 1 & 2 Belorussian, 1 Ukrainian Fronts and 18 Long Range Air Army. In the first phase, getting thru the Oder-Neisse line the breakthrough sector was 8 Gds Army on a 7 km front with 310 gun, mortars and RLs per km depoyed between 1 and 7 km from the forward edge of German defences. This sort of density on breakthough sectors was fairly common in 1944-5. The point to remember is that the overall attack frontage was several hundred km and 1 Belorussian (which included 8 GTA) alone had a frontage of 150 km. Sometimes the gun figures include anti-tank guns, my understanding is that these Sovs never used these for indirect fire so adding them in gives an inflated figure (if you count anti tank guns as arty you might as well count tanks that way). The Brit equivalent of a 75mm was the 3.7-inch How, a mountain gun, less range but a heavier shell than 75mm. 25-pdr was the equivalent of 105mm How, but greater range and lighter shell. The most obvious difference between Brit and US in WW2 was the US, as I understand it, never had btys with more than 4 guns, whereas most Brit btys had 8. Fire control arrangements were also very different, the Brits practised control from the front, the observers gave orders and controlled fire tactically, the CPs in btys controlled fire technically. The US used control from the rear, observers 'requested' and battalion FDCs controlled fire tactically and technically.

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Gilbert RE:75MM Pack Howitzer 6/8/2005 3:59:36 PM

I've been looking for a good photo of the Pack Howitzer in use, and found some at: link In particular, link looks like the emplacement that FSV has described. Another photo at link is very interesting to me. I noticed that it has two hand wheels, one of which the gunner seems to be turning. Our gun doesn't have those wheels, but it does have two crank handles that appear to be made of aluminum. You can see a photo of our gun at link I assume that these handles, or wheels, are both for setting the elevation but that the wheels are only used on the M8 carriage. I don't know why there would be a difference. I'm also confused about why the gunner would be adjusting the elevation while looking through the sight unless there is some sort of range-finding optics in the sight. Can you please comment on this?

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Gilbert RE:75MM Pack Howitzer 6/8/2005 4:08:49 PM

I guess that I shouldn't have put carrot marks around my web page references. I'll try them again. ...and found some at link In particular, link looks like the emplacement that FSV has described. Another photo at link is very interesting to me. ...You can see a photo of our gun at link

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FSV RE:75MM Pack Howitzer 6/9/2005 1:40:55 AM

I just check in my zeroxed copy of TM 9-320, dtd June 21 1941; 75 mm Howitzter Materiel. The gunner's sight was a Panoramic Telescope, M1 on a Telescope Mount, M3. This sight was used for both "indirect" & "direct" fire. The required Deflection & Elevation or Range (for 'direct fire') data was set 'on' the sight. Then the gun was 'layed'(aimed) for def. on the target reference point (Aiming Stake). The gun was then elevated to 'center' the elevation bubble (this looks just lie a 'carpenter's level'). When the bubble was centered, the elv. data had been applied to the gun. In the picture, the gunner does not appear to have his eye all the way "up on" the sight. So he is probably looking at the 'site level' (located on the Panoramic Telescope), as he elevates the gun to "center" the 'bubble'. A 'good' gun crew would put a "Zero QE" [quadrant elevation] reference mark on the gun's aiming stake. This allowed the gunner to do a complete lay of the gun, without 'coming off' the sight. This allowed a faster laying of the gun. The "75 Pack" was mainly used in the 'direct fire' mode and sometimes in the 'direct fire' mode (especially during the early phases of the amphibious landings). Rarely was it employed in the Front Lines. In 1927, the German Army started issuing, to the infantry Bn's, the 7.5 cm Light Infantry Gun, which was also known as the 7.5 cm Le. I.G. 18. This howitzer was designed, from the begining, to move with assaulting infantry units and provide 'close' 'direct fire' support. It was also used in the 'indirect fire' mode. Here is some data: Muzzle velocity (HE, max) = 222.5 meters per second (m/s). Range, max (HE) = 3,538 meters. Rate of fire (max) = 15 to 20 rounds per minute. Elevation = -177 mils (-10 deg) to +1,292 mils (+73 deg). Traverse = 106 mils (6 deg) left/right of 0. Weight (in action) = 400 kg (880 lb). Ammunition = High Explosive (HE) w/ several propellant charges and Hollow Charge (ie High Explosive Anti- Tank). The gun, with limber, was drawn by 6 horses (reguardless of the Propaganda Films, the German Army depended upon horses for the majority of its transportation needs til the end of WW2) or light truck/half-track. The gun could be pulled by 4 men, the harnesses were part of the 'issued' equipment for the gun. I did see a picture were the gun was being pulled by 1 of those german half-track motorcycle's, with another 'tracked cycle' pulling an ammo trailer. The gun could be 'broken-down' into 6 pack loads (165 lbs max each). The gun carriage was a 'closed box' type, like the US M1 carriage. The breach was a 'shotgun' style. The rear of the barrel tilted up/open just like a 'single shot' shotgun, to be loaded.

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Gilbert RE:75MM Pack Howitzer 6/9/2005 11:59:52 PM

Thanks FSV. I assume you meant, "the pack howitzer was mainly used in the 'indirect fire' mode and sometimes in the 'direct fire' mode. Is that correct? If so, I think I've got the gist of the sight operation and elevation setting. But what about azimuth? There is a brass wheel under the barrel at the front of the carriage that appears to be the device for moving the aim to the left and right. However, that seems like an awkward way to do it. A person would have to reach behind that left wheel and turn the brass handle, wouldn't he? How is the azimuth setting done? By the way, I apologize down to my socks -- the address I gave for the photo of our cannon was incomplete. It is at: link While I'm showing photos of our gun, please look at: link I'm guessing that that is the "trigger," for want of a better word. Is that what it is, and if so, what is the correct name for it. I've seen howitzers fired on TV by one of the crew pulling a cord, and I assume that that cord is attached to the handle (welded in place) shown in this photo.

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