Chemical and other special warfare units

Started by Darman, January 17, 2015, 11:12:16 AM

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Kaiser Kirk

Quote from: Darman on January 19, 2015, 10:58:15 PM
Proposal:
Each army corps (50,000 men) requires 1 chemical regiment (1,000 men) to provide full defensive chemical protection.  (If two opposing army corps each have a chemical regiment attached of equivalent technology level then there is no advantage to be gained by either side in using chemical weapons.
... 
Edit: Sorry for the massive blocks of text and long-winded explanations.  The more I've been exploring this topic on my own the more fascinating I find it. 

A couple of points.
1. We're only supposed be buying stuff in Division sized units in the first place. It seems strange to introduce a solitary 1,000 man unit that must be mated to paired divisions.
2. The massive blocks of text and long winded explanations are fine, and I certainly appreciate the idea of being fascinated with something you find unappealing.
Can't recall the exact quote - It is well war is so awful, else man would grow fond of it...

3. I'd much rather this topic be dealt with like motorization - you note in your OOB if the unit is motorized, Chemical resistant, etc.  If we want, we could class a Chemical Offensive unit as a type of Siege Artillery that can be bought.
4. Overall, I liked Kworld's system, and was happy with the complexity....of course I've tinkered with TO&Es ever since Traveller days, but unless we're actually adopting it as an option, I'd like to stay away from peicemealing in specialist units.
Did they beat the drum slowly,
Did they play the fife lowly,
Did they sound the death march, as they lowered you down,
Did the band play the last post and chorus,
Did the pipes play the flowers of the forest

Darman

Quote from: Kaiser Kirk on January 20, 2015, 11:16:14 PM
Quote from: Darman on January 19, 2015, 10:58:15 PM
Proposal:
Each army corps (50,000 men) requires 1 chemical regiment (1,000 men) to provide full defensive chemical protection.  (If two opposing army corps each have a chemical regiment attached of equivalent technology level then there is no advantage to be gained by either side in using chemical weapons.
... 
Edit: Sorry for the massive blocks of text and long-winded explanations.  The more I've been exploring this topic on my own the more fascinating I find it. 

A couple of points.
1. We're only supposed be buying stuff in Division sized units in the first place. It seems strange to introduce a solitary 1,000 man unit that must be mated to paired divisions.
2. The massive blocks of text and long winded explanations are fine, and I certainly appreciate the idea of being fascinated with something you find unappealing.
Can't recall the exact quote - It is well war is so awful, else man would grow fond of it...

3. I'd much rather this topic be dealt with like motorization - you note in your OOB if the unit is motorized, Chemical resistant, etc.  If we want, we could class a Chemical Offensive unit as a type of Siege Artillery that can be bought.
4. Overall, I liked Kworld's system, and was happy with the complexity....of course I've tinkered with TO&Es ever since Traveller days, but unless we're actually adopting it as an option, I'd like to stay away from peicemealing in specialist units.

1. Lest anyone believe I'm advocating 1,000 man units my original idea was actually the creation of a 5,000 man brigade (which I personally have at least 3 of in my orbat) and then simply make the mods aware at the beginning of hostilities that 1/5 of your brigade (otherwise referred to as a regiment) is assigned to support X corps (or 2 concurrently deployed divisions).  I realize the end result is more or less the same, but for bookkeeping purposes you only have to keep track of one brigade. 

2. I believe that quote has been attributed to General Lee.  But I'm not absolutely positive. 

3.  If general consensus is against adding a specialist unit then I would happily accept a system whereby we pay for chemical defense (a la motorization) and pay for each incidence of chemical weapons usage (my preference would be to require stocks to be produced in advance). 

Walter

QuoteI don't know what years you were in the army, but you are absolutely right, outside of the largest formations (i.e. if the Soviets had invaded Europe during the Cold War there would have been brigade-sized CBRN units assigned to the entire theater of operations, which would have then been divvied out on an as-needed basis) it would never have been a full regiment providing support.  However, in addition to protective suits and respirators, which I'm sure you were trained to use and equipped with, there were chemical companies or platoons assigned to every division or brigade (today each Brigade Combat Team has a CBRN platoon in its organic TO&E), their job would be CBRN reconnaissance and initial and basic decontamination procedures, with the goal of retaining mobility and combat effectiveness in the face of a CBRN attack.  The size of a CBRN platoon in terms of manpower is about 1% of its parent organization's manpower.  This correlates well with the size of the Chemical Warfare Service's manpower deployed in Europe in November of 1918, which was about 1% of the total American Expeditionary Forces in France.
Early/mid 1990s. We had a field exercise one day where we had to wear suits and respirators and walked around on patrol... but it was but it was a natural area which was popular to visitors (not an enclosed military area) so I wonder what the people were thinking when they saw us all dressed up in protective gear. :)

But you mentioned 'defensive chemical protection' which is your protective suit and gasmask. What you are saying now is something different. CBRN reconnaissance and decontamination procedures are aspects that do require specialists, but I do not associate with 'defensive chemical protection'.
QuoteWhether its using a separate unit or adding an ability the way we add motorization, it matters little to me.
To me, using it as an 'ability' of a division/corps could be considered like adding such a regiment to the TOE of that division/corps. But the difference is that with making it an 'ability' you're not just paying for that specialist regiment to be raised and integrated into the TOE of the Division/Corps, but you are also paying for the protective gear for the whole division/corps as well as training that comes with using that gear. Adding a specialist regiment to a division/corps does not add anything to defensive chemical protection, just prevention and treatment. The best thing one could do is detect a chemical attack, retreat quickly and treat those who get injured in the attack. No gasmasks, no protection.
QuoteThe US had chemical mortar battalions in WW2 whose job it was to handle chemical munitions in addition to providing smoke, white phosphorus, and high explosive munitions fire support to infantry divisions on the frontlines.  These units were in high demand and generally reassigned to the frontline division when units were rotated off the line.
An offensive mortar unit like that could be separate as would units be that handle and operate gas cylinders like this...

... or something like working with Livens Projectors like this...


But as you said, the US had that in WW2. Was this also the case in WW1? And what about pre WW1? I could see something simple along the line of the siege artillery unit for something like chemical attack units just like Kirk said, but instead of it being linked to the tech level of infantry like the siege artillery unit, it is fairly obvious that the chemical attack unit should be linked to the tech level of the CBR warfare.
QuoteAll Soviet Divisions in 1941 had at least a chemical company attached, and yet the Soviets did not use chemical weapons when they were being overrun.  Perhaps through fear of retaliation, but its also theorized that following the virtual collapse of the initial Soviet defenses, there wasn't sufficient organization to effectively utilize chemical weapons against the advancing German columns.  Such usage would have forced the Germans to avoid contaminated ground, and to completely decontaminate all affected units, forcing a slow-down in their operational tempo.  German forces facing the Soviets had chemical decontamination battalions attached to certain corps, approximately 25% of German corps had a chemical decontamination battalion attached, possibly more, the orders of battle for some units were rather sparse.  Of units assigned to strategic reserve or garrison duties during that time none had chemical battalions attached.  A Finnish army corps attached to Germany's Norwegian forces had 3 chemical companies, one at the corps-level and another attached to each division.
Nice and useful stuff, especially considering that we work with Divisions.

... but I'm pretty sure you were talking about protective equipment of the US Army, not about attached chemical units. :)
Quote1. We're only supposed be buying stuff in Division sized units in the first place. It seems strange to introduce a solitary 1,000 man unit that must be mated to paired divisions.
Well, you mentioned them... the siege artillery batteries are separate small units. I'm pretty sure that there would be less than 1,000 men in such a battery. I'm not sure about their status in this version of Navalism, but light and heavy armored units were also separate small units in previous versions of Navalism.

snip

I think this needs to be broken off into two separate topics.

1. Do we want to change the way that army units are handled?

2. How do we want to handle specialists items (AT, AA, NBC protection, etc)?
You smug-faced crowds with kindling eye
Who cheer when solider lads march by
Sneak home and pray that you'll never know
The hell where youth and laughter go.
-Siegfried Sassoon

The Rock Doctor

1. I'm open to customization of army units, to a point.

2. I'd prefer to see specialist capabilities applied in the simplest way possible - the tech means you have it, or you pay some flat fee to upgrade your unit.

Darman

Quote from: Walter on January 21, 2015, 07:59:34 AM
But you mentioned 'defensive chemical protection' which is your protective suit and gasmask. What you are saying now is something different. CBRN reconnaissance and decontamination procedures are aspects that do require specialists, but I do not associate with 'defensive chemical protection'.
My apologies for the miscommunication, I kept using that terminology, which in my mind encompassed attack warning (reconnaissance) and decontamination, without ever fully explaining it. 

QuoteTo me, using it as an 'ability' of a division/corps could be considered like adding such a regiment to the TOE of that division/corps. But the difference is that with making it an 'ability' you're not just paying for that specialist regiment to be raised and integrated into the TOE of the Division/Corps, but you are also paying for the protective gear for the whole division/corps as well as training that comes with using that gear. Adding a specialist regiment to a division/corps does not add anything to defensive chemical protection, just prevention and treatment. The best thing one could do is detect a chemical attack, retreat quickly and treat those who get injured in the attack. No gasmasks, no protection.

I agree that under a literal interpretation you are correct.  However, to my mind, the attachment of a chemical warfare unit to a division/corps would be the equivalent of adding the CBRN platoons to each brigade, plus one or two companies at higher HQ-level, and the unit in addition would bring with it sufficient stocks of gas masks (and suits, eventually).  Hence my stipulation at one point that a single regiment would be required to cover an entire corps -it simply doesn't bring with it sufficient gear to protect more than one corps worth of personnel and equipment.  Is it precisely the real-world equivalent?  Absolutely not.  My goal in making the proposal (and bringing this up in the first place) has more or less been achieved, in that it has sparked a lively discussion, and hopefully we will achieve something in the end.  I made a proposal that I felt had the possibility of being rather simple and straightforward, covering as much ground as possible without significantly altering our existing system. 

QuoteAn offensive mortar unit like that could be separate as would units be that handle and operate gas cylinders like this...
....snip.....
But as you said, the US had that in WW2. Was this also the case in WW1? And what about pre WW1? I could see something simple along the line of the siege artillery unit for something like chemical attack units just like Kirk said, but instead of it being linked to the tech level of infantry like the siege artillery unit, it is fairly obvious that the chemical attack unit should be linked to the tech level of the CBR warfare.

Pre-WW1 I know nothing about except that the French had a tear-gas grenade that they used during the maneuver phase of the war but because it was used in the open the gas couldn't concentrate (it'd been designed for use against bunkers) it was deemed ineffective and discontinued. 

The British has Royal Engineer "Special Companies" that specialized in offensive chemical warfare.  The Germans had battalions (at least 9), and the French had at least 3 battalions all devoted to offensive chemical operations.  The US had one "Gas and Flame" Regiment.  The "flame" was later dropped, after it was decided that the primitive Allied flamethrowers in existence were more a danger to friend than foe. 

I'm attempting to dig through a paper about chemical warfare in WW1.  So far before American involvement in 1917 absolutely zero thought was given to chemical warfare by any military authorities in the US Army.  The Dept of Interior's Bureau of Mines offered to do research on an effective gas mask utilizing its past experience with noxious fumes in underground mines.  Upon the rejection of 25,000 hastily-manufactured masks by British inspectors, the Army Medical Corps was informed it had to supply 1 million masks, 8,500 sprayers for decontamination, and 1,000 oxygen-somethingish machines (for treating poison gas casualties) within a year. 
As untrained (in chemical warfare) American troops are sent to France a "Gas Service" is being created in France on the fly.  British advisers maintained that simply handing out gas shells to trench mortar units would not work, that it required specialist units to handle gas shells.  (The Germans were issuing gas shells to artillery batteries at a rate of 50% of shells supplied, however, no mention is made of British artillery units, only trench mortars.  the British also preferred canister- and projector-released gas clouds, so presumably the 4" Stokes mortar counts as a "projector".)  Additionally, the Americans decided that all of their chemical warfare officers should be cross-trained in both offensive and defensive operations.  In 1918 the Gas Service was allowed to assign officers to division-level headquarters and above to be Chief Gas Staff Officers, these officers having been trained to serve in the offensive Gas Engineer Battalions as well.  Regimental, battalion, and company-levels all had several officers and/or NCOs who were sent to a special Gas Defense School and were in charge of their unit's gas defenses.  American divisions also established gas casualty-specific hospitals, one for each division. 

Army logistics created a subclassification for gas-related category 5 munitions. 
A was munitions issued to combat troops (gas shells and grenades)
B was munitions issued only to specialist troops (projector and trench mortar ammunition, gas canisters, etc)
C was munitions for smoke, aviation, and incendiary purposes
D was defensive chemical equipment

The Gas Service was in charge of subtypes B and D: thus in charge of training and equipping troops for defensive as well as offensive chemical operations. 

Quote... but I'm pretty sure you were talking about protective equipment of the US Army, not about attached chemical units. :)
Yes.  The numbers I found referred to the protective equipment.  Such low levels of protection would tend to discount any large-scale offensive preparations for chemical warfare.  After all, why would any armed forces utilize chemical weapons if their own troops are not equipped or trained to operate in a chemical environment? 

Darman

Okay, sorry for making this two posts, I'm sure you are all wanting to kill me right about now. 

Anyways, I'm going to rewrite my original proposal and add an alternative as well.  I'll try to explain the rationale behind both, but bear with me as I'm surprisingly exhausted despite it only being midnight (I'm normally up to 2am or so). 

Proposal 1: Gas Regiment

Mechanics: Gas units can be purchased (cost TBD) in any size (Regiment through Corps) with 1 Corps being the equivalent of 50 Regiments (50,000 men divided into 1,000 man units).  Said unit would be subdivided during a war and attached to military units, each regiment providing protection, decontamination, and specialized medical care to at most 1 Corps (50,000 men). 

The regiment represents approximately a battalion-sized unit that is subdivided into companies, platoons, and detached individuals spread out amongst the entirety of the unit it is attached to with the purpose of disseminating training and gear for chemical warfare, both defensive and offensive.  The cost for creating and maintaining this regiment covers its organic stockpiles of protective and decontamination equipment sufficient for 1 Corps, the maintenance of said equipment, extra training for the personnel of the regiment and also extra training sessions for the personnel of whatever unit the regiment is currently attached to. 

The Gas Regiment's level would be associated with the chemical warfare technology level of the nation in question.  Regiments do have to be upgraded. 

Proposal 2: Upgraded Units

Army units can be upgraded similarly to the motorization upgrade.  Levels of CBRN Defense upgrade would be dependent upon the technology level of the nation (or if equipment is purchased from abroad that may be acceptable).  (Costs of initial upgrade and all subsequent levels TBD.)
Offensive CBRN weapons would be best represented by single-use "Chemical Warfare" devices.  Each device being a single division-strength attack and costing $0.25 to produce.  [My recommendation would be that there is a requirement to produce said weapons prior to use, thus making it impossible for someone with a sudden tech advantage to mass-produce an overwhelming amount of chemical ordnance within one turn, given that chemical weapons as a surprise have been proven to be effective historically.  This still allows for that, but presumably spies can alert an opponent of someone is stockpiling 10 million tons of chemical weapons.]



Modification to Proposal 1: One possible modification is that the chemical regiment only consist of defensive measures, that offensive chemical actions are paid for as in Proposal 2. 


I kinda feel like I sound like I'm just defending my proposal, yet I really am open to alternatives and/or modifications.  If you'd like me to explain why each of the proposals would be historically realistic, I can do my best, but I'm not wedded to either proposal.  As my "modification" shows I actually think a combination of the two may be best.  But I really don't know. 

Kaiser Kirk

Quote from: Darman on January 21, 2015, 12:08:42 AM
1. Lest anyone believe I'm advocating 1,000 man units my original idea was actually the creation of a 5,000 man brigade (which I personally have at least 3 of in my orbat) and then simply make the mods aware at the beginning of hostilities that 1/5 of your brigade (otherwise referred to as a regiment) is assigned to support X corps (or 2 concurrently deployed divisions).  I realize the end result is more or less the same, but for bookkeeping purposes you only have to keep track of one brigade. 

2. I believe that quote has been attributed to General Lee.  But I'm not absolutely positive. 

3.  If general consensus is against adding a specialist unit then I would happily accept a system whereby we pay for chemical defense (a la motorization) and pay for each incidence of chemical weapons usage (my preference would be to require stocks to be produced in advance).

1. I've noted China has odd sized units as well.  I rather wish I had done that with the Marines vs. Alpine & Cabanarie , but the idea was you bought Division sized units and so I have 25,000 marines vs. 23,919 men actually manning the ships. Of course the "tail" element of the Navy means there's more sailors overall, but I digress.

2. I'm pretty sure I got it slightly off, but yes, attributed to R.E.Lee at the Battle of Fredericksburg, in regards to the Union debacle in front of Marye's Heights. 
For non-civil war buffs, that was an a slaughter as charge after charge came across an open field against 6 deep infantry on a sunken road, using a stone wall as breastworks, backed by a hill with cannon on it....all day. They never even reached the wall.

3. That works for me.
Did they beat the drum slowly,
Did they play the fife lowly,
Did they sound the death march, as they lowered you down,
Did the band play the last post and chorus,
Did the pipes play the flowers of the forest

Kaiser Kirk

Quote from: Darman on January 21, 2015, 10:30:02 PM
Okay, sorry for making this two posts, I'm sure you are all wanting to kill me right about now. 

Anyways, I'm going to rewrite my original proposal and add an alternative as well.  I'll try to explain the rationale behind both, but bear with me as I'm surprisingly exhausted despite it only being midnight (I'm normally up to 2am or so). 

Proposal 1: Gas Regiment

Proposal 2: Upgraded Units

Modification to Proposal 1: One possible modification is that the chemical regiment only consist of defensive measures, that offensive chemical actions are paid for as in Proposal 2. 


I kinda feel like I sound like I'm just defending my proposal, yet I really am open to alternatives and/or modifications.  If you'd like me to explain why each of the proposals would be historically realistic, I can do my best, but I'm not wedded to either proposal.  As my "modification" shows I actually think a combination of the two may be best.  But I really don't know.

A) Nope, don't want to kill you

B) I make myself go to bed by midnight, as I'm far more congenial at 7am when I show up for work. Still, I'm quite tired now, my mental processes are not terribly sharp right now, and I'm feeling chilled even though it's only 58F or so.... I wonder if I'm fighting something, may go to bed at 11 !  Now that is digressing. But you started it. 8p

C) I prefer proposal 2. Minimal book keeping, easy to quantify how many chemical attacks, etc.  I rank em, 2, 1, mod1. 

D) There's defending the proposal, and then there's trying to explain stuff enough so other folks get why this is a good idea. Two slightly different things. You've got something you think is the Cat's Meow, how do you show others how that looks like? Meanwhile if anyone has a Dog's Bark they want to show folks.. ok.   Yes, deliberately mixing visuals and sonics there.

E) There's historically accurate, and "good enough for game play".  If we're going to complicate armies, I want more IC...because I have a feeling they will get more expensive. For good or ill, a simplified land system was chosen. I actually would have preferred a complicated one. Now, you've made the case that chemical defense/offense shouldn't be automatic for historical accuracy reasons, so I'll choose the minimal complication of Proposal 2.

F) And that takes care of my navalism writing for the night... still tinkering with 1904 designs. Do you think if I pump helium into them, and reduce the light tonnage, I can pay less for them?
Did they beat the drum slowly,
Did they play the fife lowly,
Did they sound the death march, as they lowered you down,
Did the band play the last post and chorus,
Did the pipes play the flowers of the forest

Darman

Quote from: Kaiser Kirk on January 21, 2015, 10:48:37 PM
F) And that takes care of my navalism writing for the night... still tinkering with 1904 designs. Do you think if I pump helium into them, and reduce the light tonnage, I can pay less for them?
Depends... if the gas you pump into your ships is toxic it'll cost you $0.25 per ship, but the ship might be lighter....

Edit: and this response is how I know its time for bed.  Goodnight!

Walter

QuoteHowever, to my mind, the attachment of a chemical warfare unit to a division/corps would be the equivalent of adding the CBRN platoons to each brigade, plus one or two companies at higher HQ-level, and the unit in addition would bring with it sufficient stocks of gas masks (and suits, eventually).  Hence my stipulation at one point that a single regiment would be required to cover an entire corps -it simply doesn't bring with it sufficient gear to protect more than one corps worth of personnel and equipment.  Is it precisely the real-world equivalent?  Absolutely not.
Maybe it is not entirely realistic either, but I feel that making it an ability would make it easier. No need to worry about whether it is the right size or if there are enough units in the Corps or Division. No shuffling around of units to other Corps/Divisions either so no additional headache for the mods to keep track which Corps/Divison has CBRN units now and which ones no longer have them. But that is how I look at it.
Quote1. I've noted China has odd sized units as well.  I rather wish I had done that with the Marines vs. Alpine & Cabanarie , but the idea was you bought Division sized units and so I have 25,000 marines vs. 23,919 men actually manning the ships. Of course the "tail" element of the Navy means there's more sailors overall, but I digress.
It is that you mentioned that, but I forgot about that (probably due to the fact that they are still divisions eventhough they are not 25000 men divisions). The original plan was for something different, but when I realized that the cost and upkeep in the speadsheet depended on the number of men in the unit, I altered it to what it is now. 10,000 men for cavalry divisions, 15,000 for specialist divisions and 25,000 for infantry divisions. Looking at it now, I still have to give them the proper combat values in the encyclopedia...
Quote2. I'm pretty sure I got it slightly off, but yes, attributed to R.E.Lee at the Battle of Fredericksburg, in regards to the Union debacle in front of Marye's Heights.
For non-civil war buffs, that was an a slaughter as charge after charge came across an open field against 6 deep infantry on a sunken road, using a stone wall as breastworks, backed by a hill with cannon on it....all day. They never even reached the wall.
Well, that was Lincoln's fault. He should not have given him the command of the Army of the Potomac to Burnside (who IIRC objected to it).

... Of course, if McClellan had still been in command, there would not have been a battle at Fredricksburg. He'd still be wiring around Christmas to Lincoln that he needed more troops because there were 250,000 rebels in front of him...

... Christmas 1865 that is. ;D



Kaiser Kirk

Quote from: Walter on January 22, 2015, 07:05:34 AM

Well, that was Lincoln's fault. He should not have given him the command of the Army of the Potomac to Burnside (who IIRC objected to it).

... Of course, if McClellan had still been in command, there would not have been a battle at Fredricksburg. He'd still be wiring around Christmas to Lincoln that he needed more troops because there were 250,000 rebels in front of him...

... Christmas 1865 that is. ;D

Correct, Burnside told Lincoln he wasn't up for the job and objected to being promoted.
In Burnside's defense, when he figured out what he had ordered his men into, he wanted to try again the next morning, but he would lead - which would have been suicide.  Which indicates a level of remorse on top of self awareness. Meanwhile, one of the Union commanders that had the most success on that day was a fellow by the name of Meade.
Sadly, Burnside remained in command of a independent Corps, which led to a disjointed command structure later in 1864.

As for Little Mac, can one imagine him replacing Hooker after Chancellorsville, and trying to react to a meeting engagement at a place called Gettysburg....
Did they beat the drum slowly,
Did they play the fife lowly,
Did they sound the death march, as they lowered you down,
Did the band play the last post and chorus,
Did the pipes play the flowers of the forest

Darman

Quote from: Walter on January 22, 2015, 07:05:34 AM
Maybe it is not entirely realistic either, but I feel that making it an ability would make it easier. No need to worry about whether it is the right size or if there are enough units in the Corps or Division. No shuffling around of units to other Corps/Divisions either so no additional headache for the mods to keep track which Corps/Divison has CBRN units now and which ones no longer have them. But that is how I look at it.
I can agree to making it an ability, if that seems to be the simplest method.  But chemical attacks themselves must be paid for, and preferably produced a turn ahead of use. 

Also, I've discovered through my reading that gas attacks were very successful when used towards gaining limited objectives: breaching the trench-line being a little beyond the current technical capabilities.  Use of aircraft-carried chemical weapons was extremely limited, this would be the only reliable method of delivery capable of creating a large enough gas cloud behind enemy lines as well as over the trenches and artillery emplacements themselves, which could easily be done by artillery, "beam" canister attacks, and trench mortars/projectors. 
Additionally, the technology of the Allies and Germans being roughly equal for most of WW1 while neither side ever gained a definitive advantage overall, there were many successful chemical attacks against theoretically equal tech level defenses.  I believe that a chemical attack against a defender with equal technology should have a 50% chance of success.  Attacks against those with lesser chemical warfare tech would automatically be assumed to have worked. 

Kaiser Kirk

Quote from: Darman on January 22, 2015, 09:44:44 PM

Additionally, the technology of the Allies and Germans being roughly equal for most of WW1 while neither side ever gained a definitive advantage overall, there were many successful chemical attacks against theoretically equal tech level defenses.  I believe that a chemical attack against a defender with equal technology should have a 50% chance of success.  Attacks against those with lesser chemical warfare tech would automatically be assumed to have worked.

Well, the defender normally has the advantage, so the odds of success- everything being even- should be less than 50% to start with.
As for automatic success - there were times where simply weather foiled the successful employment of gas - particularly when large preplanned attacks with time tables are concerned.
I believe the gasses also tended to be low lying (could be off on that), which would make terrain a big deal in potential effectiveness.  Dispersed defenses would also be a problem due to the need to build up a concentration. 

Trying to look up a British employment where shifting wind pushed the gas back on the British, the Wiki article on poison gasses includes gas failing because the shell froze in Jan 1915, gas attacks at 2nd Ypres which didn't breach the lines, and a Russian fortress gassed, but held - all 1915 before defenses would be widespread. ...indeed at 2nd Ypres only the chemical weapons handlers had defenses.

ahh here we go- terrain " and that those who stood up on the fire step suffered less—indeed they often escaped any serious effects—than those who lay down or sat at the bottom of a trench. Men who stood on the parapet suffered least, as the gas was denser near the ground. "

So... Shifting a column, or two, depending on the gas, the amount of gas-delivering resources relative to the battle, and disparity in offensive/defensive techs, sure. Automatic success no.
hmm fun stat - 100,000 gas deaths in WW1, and 180,000 tons produced (unknown how many used).

And here a little story.
When my dad was young, they got their eggs from the guy up the hill- the "Chicken man". Who my dad said couldn't speak because his vocal cords were burned out in WWI by mustard gas.
Charming stuff.
Did they beat the drum slowly,
Did they play the fife lowly,
Did they sound the death march, as they lowered you down,
Did the band play the last post and chorus,
Did the pipes play the flowers of the forest

Kaiser Kirk

QuoteFor mustard gas, which could cause severe damage by simply making contact with skin, no effective countermeasure was found during the war. The kilt-wearing Scottish regiments were especially vulnerable to mustard gas injuries due to their bare legs. At Nieuwpoort in Flanders some Scottish battalions took to wearing women's tights beneath the kilt as a form of protection.

I find that oddly humorous.
Did they beat the drum slowly,
Did they play the fife lowly,
Did they sound the death march, as they lowered you down,
Did the band play the last post and chorus,
Did the pipes play the flowers of the forest