Operation No. 3: Hide and Seek – Information and ISR in A Hot Dry Season

Different Sides, Different Forces, Different Capabilities, Similar Problems

Any discussion of Intelligence, Surveillance and Reconnaissance (ISR), hidden information and limited information in A Hot Dry Season (AHDS) has to begin with the following conundrum; the two sides had very different forces with very different capabilities, which require significant differences in how their forces are represented in the area of operations.  However, both sides had to overcome similar difficulties regarding the terrain of War Zone C in order to obtain battlefield information regarding enemy presence, identification and disposition in order to possess a common operating picture and situational awareness of what was occurring in the operation.

A constant recurring theme when I was researching Operation Attleboro was how different the People’s Liberation Armed Forces of South Vietnam (PLAF), People’s Army of Vietnam (PAVN), Local Force Viet Cong (LF), the United States Army and Army of the Republic of Vietnam (ARVN) were from each other.  Another recurring theme was how dynamic these force structures were from year to year (both sides) and from region to region (mainly the NLF).  Very different structures and capabilities were available, depending on the operational “snapshot” taken in time and space.  There are very few, if any, general truisms or rules of thumb that can be applied to these forces, how they disposed themselves and their capabilities that can be applied from one year to the next, or from region to region within South Vietnam.  At the operational echelon.


The PLAF and the PAVN shared many commonalities due to a shared military heritage and a singular strategic command and control parentage in the Politburo in 1966.  Many differences were present as well. One reason was the primary source of recruits since 1961; the PLAF from the Southern Vietnamese population and the PAVN from the Northern Vietnamese population, though northern recruits to the PLAF were already becoming quite common by 1964.  They used the same equipment, generally.  However strong differences in levels of training and exercising command relationships in the field stand out.  Generally speaking, at this stage of the War, the PLAF were better trained, had more experienced soldiers, NCOs and Officers, and were better acclimated to and experienced with the demands of combat in South Vietnam and operating in the rugged terrain.  The PAVN was beginning to catch up however, and some PAVN regiments and divisions had been operating in South Vietnam for one to two years and had become “seasoned” over time.  This was not the case in War Zone C, nor in the III Corps Tactical Zone (III CTZ) in November 1966.

The PLAF and LF units in the area of operations modeled in AHDS while very familiar with each other and operationally coordinated together well, with the PLAF having many members who began their military and revolutionary careers in those very LF units.  These forces were very different, however, as they were organized and used for very different purposes.  LF units were conducting “classic” guerrilla operations normally, and the battalions present in the game had “formed up” into battalions (something they were unaccustomed to doing) expressly to support the Dry Season offensive in War Zone C.  The PLAF, originally formed as a “big stick” to protect revolutionary efforts and guerrilla cadres when threatened by the ARVN, had grown from independent battalions to then include independent regiments and, also divisions between 1961 and late 1964.

However, all these NLF force structures, while different, shared some commonalities.  In 1966 all these structures emphasized man-portable equipment, speed and training in maximizing the use of terrain and the human infrastructure in War Zone C to evade detection by enemy ISR capabilities.   Also, radio communications were generally only available at the regimental-level or higher, though LF Battalions usually had access to workable radio communications to coordinate with PLAF headquarters operating in the area; sometimes hidden away until notified via messenger that the time had come to form up into battalions, or provided by PLAF advance parties.  Also, here’s a surprise, the NLF had no aviation assets in War Zone C – I know, I’m as shocked as you are!  But seriously, there are other examples I will provide as this essay continues, but from an ISR evasion and detection standpoint, these are significant factors, very different from the US Army and ARVN.  The NLF relied on reconnaissance assets and local human intelligence capabilities for ISR detection of the enemy, magnified by friendly population networks that could be tapped into as well as prepared covert supply and military infrastructures that had been painstakingly build in War Zone C since 1961.  The 9th PLAF Division had a signal intelligence capability utilizing primarily radio direction finding and limited traffic analysis.


The ARVN forces in War Zone C during Operation Attleboro were Regional Forces (RF), primarily suited for static defense duties or engaging NLF LF units in smaller tactical situations.  They were no match for PLAF or PAVN formations unless defending in prepared positions.  Evasion of ISR detection was not a major consideration in their training other than standard, basic infantry tactics.  ARVN ISR capabilities were minimal; no technical intelligence or surveillance capabilities were on offer and no reconnaissance assets were present. Years of NLF domination of the area made attempts to utilize local human intelligence networks a futile effort.  In fact, the local population’s connections to the NLF and the RF and provincial government’s lack of operational security and penetration by NLF sympathizers made them vulnerable to ISR detection; a vulnerability that inevitably impacted US forces.

US Army

US Army formations present at Operation Attleboro were in a period of flux in 1966.  There are six types of battalion modification tables of organization and equipment (MTOEs) present; some test MTOEs and some standard, with the standard ones being adapted to the demands of the Vietnam War.   This is the subject of a separate essay I will write later, but this is indictive of the US Army’s dynamic nature in its force structure at this time.  These forces were generally well trained, though the 196th Light infantry Brigade (Separate) (196th LIB), due to its utilization of a test brigade concept with insufficient brigade assets to fully enable it operating as an independent command, recent arrival to the theater, and brigade command and control issues were a factor that must be considered with that unit.  US units had an abundance of command and control riches, with electronic communications down to the platoon level, but raising their ISR detection profile.  US units were also extremely vulnerable to detection by NLF human intelligence networks, and NLF sympathizers in populated areas made for easy detection of US units moving through them.

US ISR capabilities in the area of operation were superb.   A communications intelligence capability was readily available to support the area of operations with a US Army Security Agency detachment ensconced on the top of Nui Ba Den Mountain.  A signals intelligence capability was available at the 1st Infantry Division Headquarters.  Surveillance capabilities were readily available and much relied upon; US Army rotary aviation observation craft and fixed wing observation craft were predominantly used.  Four Special Forces camps with accompanying Special Forces detachments who could utilize human informant networks as value-added to their ground reconnaissance capability.  Long Range Reconnaissance Patrol teams (LRRPs) were not available for the Operation.  Though the 1st Infantry Division and the 25th Infantry Division had LRRP teams established by November 1966, those units were engaged in active operations outside of the area of operations modeled in AHDS when those divisions reinforced Operation Attleboro with subordinate formations.  The 196th LIB had no LRRP teams, a critical capability overlooked in its brigade test concept which added to its difficulties during Operation Attleboro.

So, to sum up, we have two forces, each with different profiles regarding susceptibility to ISR detection and different ISR capabilities to detect enemy units.  And then the rugged, trying terrain of the area of operations is added to that equation, along with the effects of the population dwelling there, and their impact on ISR detection.  How is all this done in game terms?



There are three different levels of information availability for units on-map in AHDS: hidden, limited and open, in game terms Concealed, Unfixed and Fixed.

Hidden information is achieved using Concealed status.  Concealment Markers (CM) practically achieve this effect, as Concealed NLF units are on a player aid card, with numbered boxes corresponding to each CM, with the CMs performing on-map movement, not the units themselves.  Concealment is a capability only available to NLF units.  CMs may be empty or contain NLF units. CMs may be revealed as empty or the units in them placed on the map via: successful US player ISR missions or overt actions by the NLF player (attacking, voluntarily revealing the CM, etc.).  There are combat benefits to the NLF player when attacking with Concealed units and combat penalties to the US when conducting fires or attacking a CM.  CMs ignore zones of control in the game.  Units which are revealed and placed on the map may be Unfixed or Fixed, depending on the specifics. For example, some (not all) ISR missions reveal the units in Unfixed status.  Attacking or conducting fires by Concealed units reveals them, Fixed.


Limited information is achieved using an Unfixed status.  Any non-motorized or non-mechanized unit, regardless of side, may be Unfixed.  All Unfixed units in a hex have an Unfixed status marker placed on them.  The other player may freely examine stacks on the map but may not examine units under an Unfixed marker.  There are combat penalties to attacking Unfixed units.  Determination of whether a unit is Unfixed or Fixed at the start of a day is made at the beginning of the turn.  Unfixed units are Fixed when they move adjacent to an enemy unit (or CM), and units adjacent to the enemy may not be Unfixed.   Unfixed units may be Fixed by the conduct of enemy ISR missions (a much easier process than revealing units that are Concealed).  Unfixed units that conduct fires missions are fixed.  Unfixed US units that move into urban areas, towns or villages are Fixed, and may not become Unfixed if in hexes with those infrastructure types.  Unfixed NLF units become Fixed if they move adjacent to a US Base, Firebase or Special Forces camp and may not become Unfixed if adjacent to hexes with those infrastructure types.


Open information is achieved using Fixed status.  There is no mechanism used for visibility on-map, they are open for examination (practically speaking, in a stack, Fixed units and any CMs are placed on top of any Unfixed status marker in the hex).   Motorized and mechanized units are always Fixed.  Any fires conducted against Fixed units receive a bonus.


ISR Relevent Sequence of Play

Hidden, Limited and Open Information statuses change during specific phases of the game turn (a day).  On the simplified Sequence of Play example seen above, determination of a Unit being Fixed or Unfixed occurs in the green step of the Command Phase above.  It’s the last thing that happens in each day’s Command Phase.

Each game turn has a First and Final ISR Phases, in red above, where a continuous battle, as important as anything that happens during the Operations and Fires Phases, occurs each day:  ISR assets and capabilities battling against the other side’s information status, and frequently against the terrain itself.  In each of those phases, the very first thing that happens is that eligible NLF units may be concealed with available CMs.



Intelligence capabilities vary in their resolution based upon the capability.  Above we see that all the units have a number in the upper right hand corner.  All units in the game have this, its called a Command Rating (CR).  CRs have nothing to do with combat; it involves the level of training/experience a unit has when determining how it resolves non-combat functions.  For the above, in this case it means how well they perform their Intelligence task.  But each capability is a little different.  The Army Security Agency (ASA) Detachment above to the far left has mechanics that involve the US player guessing (sometimes an informed guess as play proceeds) if a CM has PAVN or PLAF in the CM.  If correct the mission is successful; the CR Check is attempted on a d10 (unmodified by terrain) to determine the level of that success (are the units revealed Fixed or Unfixed).  The Signals Intelligence direction finding/traffic analysis capability of the US 1st Infantry Division HQ is similar but involves a CR check modified by terrain.  And if successful all NLF units in the CM are revealed Unfixed.  The Local Force VC Company (the 2nd of the Phu Loi Battalion is shown above) if within three hexes of a village, may Fix all Unfixed US units within 3 hexes of that village if they succeed on their CR check.  As an aside, I haven’t talked about dice in AHDS.  A d10 is used for CR checks, 2d6 are used for Fires , ADF and Ground Combat.



I said earlier, and surprised everyone reading this, that the NLF do not have air assets.  So here we are talking about US surveillance capabilities. The 1st Detachment/F Troop/17th Cavalry Squadron up there to the far left operates similarly to the 1st Infantry Division HQ, The OV-1C Mohawks of the 73d Aviation Company can operate similarly if using their “SLAR” counter side but on the above “RED HAZE” side, they can *prevent* NLF units that are adjacent from Unfixing or Concealing.  Spooky, if present in the area of operations, has a similar effect.



The US Special Forces Detachment to the upper left has a reconnaissance capability it can use to reveal a CM within 3 hexes, resolved by a CR check modified by terrain.  Any NLF Units in the CM are revealed Fixed.  It may also be used against a hex with Unfixed units.  This is automatically successful and Fixes that unit or stack. A successful CR Check modified by terrain Fixes all units in a one-hex radius of the target hex, if applicable.   The 2nd Company of the 95th PLAF Reconnaissance Battalion has the same reconnaissance capability against US/ARVN Unfixed units.

There are other game mechanics and concepts which deal with and impact ISR and Hidden/Limited information in AHDS, the above is by no means a laundry list.   Availability of information to the commander and the use of ISR capabilities to ensure it are concepts that aren’t always dealt with in wargames, but are very germane to treatments, certainly from the 20th century onward. At the operational echelon, and possibly at the tactical and strategic levels, when it comes to the Vietnam War, not having considerations for it is certainly misleading, and can lead to “the Battle of the Bulge in a Jungle”.  But as with all things, it depends of the scenario being modeled.  In Campaigns in Vietnam, in AHDS, and most importantly, to do historical justice to Operation Attleboro,  it is essential.


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