[Goose]

Very interesting, thanks so much for your informative response.  My experience in these types of things dates to the 1960's.  If you want to have a lot of fun, try carrying the base plate for an 81 mm mortar for a few hours.  As I recall the M29 system weighed nearly 100 lbs. It broke down into three components and schlepping it around in steep terrain was irrational.  As time went on, many units left their mortars at their firebases or base camps. I have no idea of what kind of mobile platform we have moving these types of weapons on the battlefield today.

Your 1960's experience is still relevant, unfortunately. There have been world-wide attempts to make a lighter 81 mm mortar that can be carried by leg infantry. Progress has been made. https://en.wikipedia.org/wiki/M252_mortar The first M252s were only marginally lighter than the M29 (two pounds less) but the M252A1 weighs "only" 79 lbs. Better but not a game-changer.

The US has always had an "eclectic" approach to moving mortars with vehicles. The current thinking is that the 120mm mortar is the best fit for vehicle use. The following list details the vehicles currently in use.https://en.wikipedia.org/wiki/M1064_mortar_carrier https://en.wikipedia.org/wiki/M1129_mortar_carrier https://en.wikipedia.org/wiki/Armored_Mu...se_Vehicle

 The M1064 is based on the M113. These vehicles are old and clearly obsolete. They need to be replaced. The replacement is being "slow walked" via very low production rates. The Stryker-based M1129 is already in fairly heavy use, particularly with Stryker brigades. It is also present in infantry formations. Unfortunately it carries with it all the survivability limitations of the Stryker. Ukraine has demonstrated that the Bradley's survivability is essential on the modern battlefield. Ukraine pretty quickly restricted the Strykers to "behind the lines" operations, and even in that role its maintenance requirements made it unpopular. The AMPV is supposed to fix that, but not everyone is "convinced". An interesting sidelight is that these vehicles carry with them an 81 mm mortar that can be dismounted and used as well. Makes ammunition supply more complicated but maybe a good idea. These assets can be both battalion level assets and company level assets depending on the type of units involved.
 
Towed mortars are also included in the US Army inventory. These mortars, while towed by vehicles like the HMMWV, can also be dismounted and emplaced for firing. The M120A1 is transported on the M326 Mortar Stowage Kit when used in that configuration. Light infantry and paratroops that have no Strykers/AMPVs. The towed mortars provide these units some indirect fire "heavy weapons" capability. However these units sometimes operate in terrain where even HMMWVs cannot operate. In that case, it is back to the troops carrying the 3 piece disassembled mortar. The M252A1 being lighter helps but obviously the guy carrying the mortar tube has an "extra" 30.5 lbs to deal with. The more serious problem is that each round of 81 mm mortar ammunition weighs about 10 pounds. In order to have meaningful weight of fires, lots of 11Bs will have to carry mortar rounds as well as everything else they need. The two "ammunition bearers" in the 5 man mortar team can possibly carry 4 rounds each, but 3 is more reasonable. That is "six and done". Arguably not worth bringing the mortar along.
 
The US Army did recognize the problem with man-packing the 81 mm mortar. By mid-1970s prototypes of the M224 60 mm mortar were being tested in Vietnam.  The current version, the M224A1 (https://jpeoaa.army.mil/Project-Offices/...MM-M224A1/), weighs 37.9 lbs. As https://www.marines.mil/Portals/1/Public...084723-267 says

The M224A1 60-mm mortar system provides Infantry, Stryker brigade combat teams (SBCTs), Ranger, and USMC rifle companies with an effective, efficient, and flexible weapon.

Each M224A1 has a crew of 3. Normally 2 such units are part of Infantry/Airbore/Ranger companies. Each company therefore has an indirect fire element that can be directly tasked by the company command team. The response time is minimal. While man-packing the M224A1 is feasible, ammunition supply remains an issue. Each HE round weighs 3.1 lbs. Carrying lots of them is still difficult. However they are approximately 1/3 the weight of 81 mm HE rounds.
 
Mechanized Infantry does not have 60 mm mortars. Carrying these devices inside a IFV would be next to impossible. These formations instead rely on the battalion level carrier mounted 120 mm mortars for indirect fire support. Of course Mechanized Infantry also has tank and IFV weapons for direct fire tasks. Forgoing the 60 mm mortars "makes sense".
 
The units referenced above may also have support from 81 mm mortars (towed, man-packed, or possibly Stryker mounted). These are battalion assets but can obviously be attached to company-sized formations. Regarding the man-pack option, the previous link states:

Note. When man-packing the M252A1 over long distances during continuous operations, the commander considers the hazard to Soldiers for an increased risk of injury and limited element maneuverability due to the weight of the system and ammunition. The commander must consider the attachment of a security element when enemy contact is possible

 

It seems to me that whoever sorts out their counter battery systems first will have a big leg up.

Indeed. However the US Army relies upon the USAF to "sanitize" the battle area of enemy artillery that could be a threat to US formations. This activity takes place before the Army even starts fighting and continues as necessary while the battle is going on. Rinse and repeat. Thus the US Army doesn't need to provide much counter-battery fire. Will this approach work in future wars? While it has in the past we better make damn sure it does because we don't have much of a plan B.
 
The army does have a counter-battery capability oriented towards a low number of targets that escaped detection/destruction. Artillery has limited range. Our opponents have to place it far enough forward to be effective. That constrains the area the USAF has to cleanse. The US Army intends mostly to use ATACMS/PrSM to destroy targets of opportunity detected by Army assets (such as counter-battery radar and direct drone observation). Right now, the Army actually does that pretty well. The problem (if any) is lack of mass. The effort is resourced to defeat the remaining less than 10% of the enemy's artillery. It can't do 100% of it.
 
In the future the Army needs to expand its ability to detect and target enemy artillery using assets other than counter-battery radar. The lifetime of such radars will be very short in the future. For our opponents, it already is. They are literally sitting ducks. That may happen to us as well, at least to a degree. The US Army needs to develop the ability technology to detect, geolocate, and target both hostile artillery and hostile counter-battery radars without "external" help. Drones will play an integral part in this process. Both ELINT and visual detection will be needed.  It is not yet possible to put a counter-battery radar in the "small" drones such as we see so often in Ukraine. The US Army should be working hard to achieve that capability however.

[Goose]

Very interesting, thanks so much for your informative response.  My experience in these types of things dates to the 1960's.  If you want to have a lot of fun, try carrying the base plate for an 81 mm mortar for a few hours.  As I recall the M29 system weighed nearly 100 lbs. It broke down into three components and schlepping it around in steep terrain was irrational.  As time went on, many units left their mortars at their firebases or base camps. I have no idea of what kind of mobile platform we have moving these types of weapons on the battlefield today.

Your 1960's experience is still relevant, unfortunately. There have been world-wide attempts to make a lighter 81 mm mortar that can be carried by leg infantry. Progress has been made. https://en.wikipedia.org/wiki/M252_mortar The first M252s were only marginally lighter than the M29 (two pounds less) but the M252A1 weighs "only" 79 lbs. Better but not a game-changer.

The US has always had an "eclectic" approach to moving mortars with vehicles. The current thinking is that the 120mm mortar is the best fit for vehicle use. The following list details the vehicles currently in use.https://en.wikipedia.org/wiki/M1064_mortar_carrier https://en.wikipedia.org/wiki/M1129_mortar_carrier https://en.wikipedia.org/wiki/Armored_Mu...se_Vehicle

 The M1064 is based on the M113. These vehicles are old and clearly obsolete. They need to be replaced. The replacement is being "slow walked" via very low production rates. The Stryker-based M1129 is already in fairly heavy use, particularly with Stryker brigades. It is also present in infantry formations. Unfortunately it carries with it all the survivability limitations of the Stryker. Ukraine has demonstrated that the Bradley's survivability is essential on the modern battlefield. Ukraine pretty quickly restricted the Strykers to "behind the lines" operations, and even in that role its maintenance requirements made it unpopular. The AMPV is supposed to fix that, but not everyone is "convinced". An interesting sidelight is that these vehicles carry with them an 81 mm mortar that can be dismounted and used as well. Makes ammunition supply more complicated but maybe a good idea. These assets can be both battalion level assets and company level assets depending on the type of units involved.
 
Towed mortars are also included in the US Army inventory. These mortars, while towed by vehicles like the HMMWV, can also be dismounted and emplaced for firing. The M120A1 is transported on the M326 Mortar Stowage Kit when used in that configuration. Light infantry and paratroops that have no Strykers/AMPVs. The towed mortars provide these units some indirect fire "heavy weapons" capability. However these units sometimes operate in terrain where even HMMWVs cannot operate. In that case, it is back to the troops carrying the 3 piece disassembled mortar. The M252A1 being lighter helps but obviously the guy carrying the mortar tube has an "extra" 30.5 lbs to deal with. The more serious problem is that each round of 81 mm mortar ammunition weighs about 10 pounds. In order to have meaningful weight of fires, lots of 11Bs will have to carry mortar rounds as well as everything else they need. The two "ammunition bearers" in the 5 man mortar team can possibly carry 4 rounds each, but 3 is more reasonable. That is "six and done". Arguably not worth bringing the mortar along.
 
The US Army did recognize the problem with man-packing the 81 mm mortar. By mid-1970s prototypes of the M224 60 mm mortar were being tested in Vietnam.  The current version, the M224A1 (https://jpeoaa.army.mil/Project-Offices/...MM-M224A1/), weighs 37.9 lbs. As https://www.marines.mil/Portals/1/Public...084723-267 says

The M224A1 60-mm mortar system provides Infantry, Stryker brigade combat teams (SBCTs), Ranger, and USMC rifle companies with an effective, efficient, and flexible weapon.

Each M224A1 has a crew of 3. Normally 2 such units are part of Infantry/Airbore/Ranger companies. Each company therefore has an indirect fire element that can be directly tasked by the company command team. The response time is minimal. While man-packing the M224A1 is feasible, ammunition supply remains an issue. Each HE round weighs 3.1 lbs. Carrying lots of them is still difficult. However they are approximately 1/3 the weight of 81 mm HE rounds.
 
Mechanized Infantry does not have 60 mm mortars. Carrying these devices inside a IFV would be next to impossible. These formations instead rely on the battalion level carrier mounted 120 mm mortars for indirect fire support. Of course Mechanized Infantry also has tank and IFV weapons for direct fire tasks. Forgoing the 60 mm mortars "makes sense".
 
The units referenced above may also have support from 81 mm mortars (towed, man-packed, or possibly Stryker mounted). These are battalion assets but can obviously be attached to company-sized formations. Regarding the man-pack option, the previous link states:

Note. When man-packing the M252A1 over long distances during continuous operations, the commander considers the hazard to Soldiers for an increased risk of injury and limited element maneuverability due to the weight of the system and ammunition. The commander must consider the attachment of a security element when enemy contact is possible

 

It seems to me that whoever sorts out their counter battery systems first will have a big leg up.

Indeed. However the US Army relies upon the USAF to "sanitize" the battle area of enemy artillery that could be a threat to US formations. This activity takes place before the Army even starts fighting and continues as necessary while the battle is going on. Rinse and repeat. Thus the US Army doesn't need to provide much counter-battery fire. Will this approach work in future wars? While it has in the past we better make damn sure it does because we don't have much of a plan B.
 
The army does have a counter-battery capability oriented towards a low number of targets that escaped detection/destruction. Artillery has limited range. Our opponents have to place it far enough forward to be effective. That constrains the area the USAF has to cleanse. The US Army intends mostly to use ATACMS/PrSM to destroy targets of opportunity detected by Army assets (such as counter-battery radar and direct drone observation). Right now, the Army actually does that pretty well. The problem (if any) is lack of mass. The effort is resourced to defeat the remaining less than 10% of the enemy's artillery. It can't do 100% of it.
 
In the future the Army needs to expand its ability to detect and target enemy artillery using assets other than counter-battery radar. The lifetime of such radars will be very short in the future. For our opponents, it already is. They are literally sitting ducks. That may happen to us as well, at least to a degree. The US Army needs to develop the ability technology to detect, geolocate, and target both hostile artillery and hostile counter-battery radars without "external" help. Drones will play an integral part in this process. Both ELINT and visual detection will be needed.  It is not yet possible to put a counter-battery radar in the "small" drones such as we see so often in Ukraine. The US Army should be working hard to achieve that capability however.