09 September 2021

BP-2 Converting a Spotting Round

Converting a Spotting Round to Fire For Effect

By James Bishop

In August 2021, I attended the ASL Scandinavian Open tournament in Copenhagen. The French have Offboard Artillery (OBA) in WO33. Walking around the room, I twice observed players Convert a Spotting Round (SR) to Fire For Effect (FFE) incorrectly. “One-Eyed Jacques” is an ideal case study for this all too common error.1

How to do it right

I have excerpted a section of the C1 Offboard Artillery Player Aid—commonly called the OBA Flowchart—that I will be referring to throughout this article. In order to Convert a SR effectively, you need to understand what’s really going on at this stage of the OBA process. Once you grasp these subtleties, you’ll increase your prospects of placing a Fire Mission significantly. And you’ll be better equipped to frustrate your opponent’s attempts to use OBA against you. For ease I have labeled the two decision-making rectangles in our section of the chart “A” and “B.” I also included the errata from ASL Journal 11, which instructs us to change “AR” (Artillery Request) to “SR” in rectangle B.2

For our purposes we will assume that you have successfully navigated the flowchart to the point where you have maintained Radio Contact, announced your intention to Convert, rolled for accuracy, and corrected the SR (if necessary). You are now ready to Convert the SR to FFE. 

It’s not enough to simply announce your intention to Convert a SR, as some players presume. There are a couple of crucial conditions that must be met before a SR can be Converted to FFE. 

Rectangle A: Determining LOS

The process begins with rectangle A. One of two conditions must be met at this stage before we can continue the Conversion process:

  1. The first condition is the most straightforward. Provided the Observer has Line of Sight (LOS) to the Base Level of the SR hex, we proceed to rectangle B. The Base Level, according to the Index, is “normally the lowest level Location” excluding subterranean Locations.3 Normal LOS rules apply with respect to Blind hexes, LOS Obstacles, LOS Hindrances, and so forth.4 
  2. Failing that, the Observer must satisfy a two-part condition. Because the Blast Height (C1.32) of a SR is visible two levels above the Base Level of a hex, it’s possible for an Observer to see a SR in an otherwise Blind Hex. Should this be case, the Observer also must have LOS to a Known enemy unit,5 either in or adjacent to the SR hex. 

For this and other OBA actions, concealed units in non-Concealment Terrain are considered Known to the Observer. (Footnote “d” after the word “Known” in rectangle A reminds us of this fact.)6 

If the Observer fails all or part of either test, we follow the “No” path to the green stadium, (hereafter oval) to the right of rectangle A, which leaves the SR in place but “unconverted.” 

In sum, both conditions rely on an Observer having LOS to where the SR has landed. The second condition is complicated by the need to have LOS to a Known enemy unit too.

Rectangle B: Converting

Let’s assume that we’ve met the tougher, Blast-Height condition in rectangle A. Following the “Yes” path to rectangle B, we are asked if are there any enemy units in or adjacent to the SR hex, in what is otherwise known as the Blast Area of a HE Concentration. And if so, are all of them unknown to the Observer? Because our Observer had to have LOS to a Known enemy unit in the Blast Area in order to get to rectangle B in the first place, we can respond with an unequivocal no. The “No” path leads directly to the green oval below, allowing us to Convert the SR to FFE:1. 

We would take the same “No” path if our Observer had LOS to the Base Level of the SR hex (rectangle A) and there were no enemy units in the Blast Area (rectangle B).7 

But what happens if all of the enemy units in the seven-hex Blast Area are unknown to the Observer? We sidestep. The “Yes” path from rectangle B leads to a square that instructs us to make an extra chit draw. 

If we draw a black chit, we proceed along the “Black” path to the green oval and Convert. Should we draw red, we sidestep again. The “Red” path leads to a rather unfriendly red oval with three, dire consequences. Not only does the SR not Convert, but it’s lost altogether. Adding insult to misery, Battery Access is also lost. 


Harassing Fire

Harassing Fire is a special case. While all rules pertaining to enemy units in or adjacent to the SR remain in play, any units located in the outermost hexes of a Harassing Fire Blast Area are ignored, regardless of whether they are Known to the Observer or not. Provided the Observer has LOS to the Base Level of the SR hex or to the Blast Height, and there are no unknown enemy units in or adjacent to the SR hex, the SR will Convert without the need to make an extra chit draw.


For this section please refer to the illustration below. The Observer is in 13aI5 on level 2. Five SR are on the board labeled SR:A through SR:E. I will discuss each in turn.

Clearly, there is more to attacking with, and defending against, OBA than offered in this brief article. If you would like to see more about this or some other topic, let me know what interests you and I may take it on. I hope you found this useful. Should you spot any errors, please let me know so that I can correct them. -- jim


1. As editor and de-facto “ghost writer,” I’ve again mutilated another of Jim’s gems. I assume full responsibility for any errors that remain or may have crept in due to my meddling. For the most part, I’ve expanded on Jim’s content, although some sections have been extensively rewritten. Hopefully, I’ve conveyed his central points in a coherent manner. Compare with his original post here.

2. You can find this errata near the top of the right-hand column of page 57 in ASL Journal 11 (2016), under the heading Charts & Tables.

3. According to the Index definition of Base Level, if the lowest level Location in building hex does not allow VBM along at least one hexside of that hex, the Base Level is that of the highest building level in that hex [EX: The Base Level of 20C7 is 2½; that of 20D7 is 0]).

4. Low Visibility conditions such as Fog (E3.31), Night Visibility Range, and artificial Illumination present special challenges for OBA Conversion that are well beyond the scope of this article.

5. Be careful not to confuse “Known” enemy unit in the context of OBA actions and “Known Enemy Unit.” The latter is defined by the Index as “any unconcealed, non-prisoner enemy unit—even one which is broken or in Melee—which the unit in question currently has a LOS to.” In contrast, an Observer will consider a concealed unit not in Concealment Terrain (e.g., in Open Ground) to be a “Known” enemy unit, as explained in the next endnote.

6. Footnote “d” on the last page of the C1 Offboard Artillery Player Aid states the following: A Known enemy unit is an unconcealed enemy that you have LOS to. However, Concealed units in non-Concealment Terrain [EXC: night, Winter Camouflage] and in LOS of the Observer are always considered Known to him for his OBA actions.

7. Hidden, subterranean, and aerial units are excluded.

Get your OBA tokens today!

03 September 2021

BP-1 Stop and Go Traffic: A Synopsis

By James Bishop

Recently players have posted questions online about Moving, Motion, Starting, and Stopping, and how these interact with C6 Target-Based To Hit DRM (Dice Roll Modifiers). These questions appear cyclically, and I can recall answering them for as long as I have played ASL. Much of the information in this article appeared in Ole Bøe’s “Stop and Go Traffic” article, which originally appeared in ASL Annual ‘96. These old Annuals are available as PDF files from MMP, or can be picked up used from all of the usual outlets. I highly recommend you read the original as it's still informative. But for those who can’t, I offer a summary of that article here.1

Moving and Vehicular Target

To apply DRM properly, it's important first to understand the difference between uppercase-Moving and “Moving Vehicular Target.” A Moving Vehicular Target, often referred to simply as a moving target, is defined in C.8. It includes any vehicle during ITS2 Movement Phase (MPh) that has a) entered a new hex, or b) Bypassed a new hexside within its current hex. In addition, any vehicle that a) starts ITS MPh in Motion, or b) is currently in Motion, qualifies as a Moving Vehicular Target. I’ll explain the concept of “Motion” shortly. The key here is that a Moving Vehicular Target is one that has either moved to a new position on the board, or qualifies for Motion status.

Moving is more nuanced. The ASL Rule Book (ASLRB) doesn’t draw a clear distinction between the two primary uses of the term in the game. In its narrowest sense, Moving refers to a unit that is currently conducting ITS MPh. I should stress that only one entity can be said to be Moving (or “phasing”) at a time. However, a Moving entity can consist of more than a single unit. Multiple units can Move as a stack, including Armored Assault (D9.31), which allows an Armored Fighting Vehicle (AFV) and Infantry to Move together. Less common is a “multi-hex stack,” which uses a form of Impulse-based movement.3 In all cases the constituent parts of any Moving group of units are considered Moving regardless of which unit (or units) are actually expending a Movement Factor (MF)/Movement Point (MP) at a given moment. For example, a stack declares Armored Assault. The AFV expends a MP to start, and another to change Vehicular Covered Arc (VCA). Although the Infantry accompanying the AFV has yet to expend any MF, both it and the AFV are Moving, that is, they are conducting THEIR MPh (as a stack). Interestingly, the vehicle does not yet qualify as a Moving Vehicular Target, although it does qualify as a target for Defensive First Fire, which brings me to the broader definition of moving, namely the expenditure of MF/MP.

Rule section A8.1 states that the “portion [of Defensive Fire] occurring during the enemy MPh is called Defensive First Fire and can be used only vs a moving unit(s).” In my previous example, the AFV expended 2 MP. The AFV is therefore moving for the purposes of Defensive First Fire and can be fired upon based on either or both MP expended. The Infantry, however, cannot be targeted directly because they have yet to expend a MF.4 A similar situation occurs when a Stopped vehicle attempts but fails to dispense Smoke at the beginning of ITS MPh. While the vehicle is Moving—in the narrowest sense of the term, it's not moving for the purposes of Defensive First Fire, because it hasn’t expended a MP (D13.2). However, were the vehicle to end ITS MPh at this point, it would qualify for Defensive First Fire, because it's considered to expend all of its remaining MP in that hex (D2.1). This is a case where a vehicle has Moved (conducted ITS MPh) without actually moving anywhere. Confusing, I know. If only such a key concept as “moving” was spelled out in the rules, or defined in the Index.

Stopped and Non-Stopped

The default setting for a vehicle that sets up onboard is Stopped (A2.52). According to the Index, a Non-Stopped vehicle is one that has not expended a Stop MP since its last Start MP expenditure during ITS MPh. A Non-Stopped vehicle is therefore a moving unit in both senses of the term “moving” discussed in the previous paragraph. On the one hand, a Non-Stopped vehicle is conducting ITS MPh. On the other hand, it's moving for the purposes of Defensive First Fire. However, a Non-Stopped vehicle is considered a Moving Vehicular Target only if it has entered a new hex, or used Vehicular Bypass Movement (VBM). So contrary to Stopped status, which can apply during any phase, Non-Stopped status can only apply to a vehicle during ITS MPh. For instance, it’s possible for a vehicle to become Stopped during an enemy Prep Fire Phase as a result of an Immobilization, Shock, or Stun result. But what happens if a vehicle chooses not to end ITS MPh Stopped? 

Motion Status

The term used to describe a vehicle that isn’t Stopped before or after ITS MPh is called Motion. A Moving vehicle—one conducting ITS MPh—is never in Motion. It's either Stopped or Non-Stopped. However, a vehicle which ends ITS MPh without expending a Stop MP assumes Motion status. This status in indicated by placing a Motion counter atop the vehicle. For To-Hit purposes, a Motion vehicle is always treated as a Moving Vehicular Target. Although the Motion counter is removed the moment a vehicle with Motion status begins ITS MPh, the vehicle remains a Moving Vehicular Target. This should be self evident given that the vehicle has yet to expend a Stop MP, and is therefore Non-Stopped, and thus a Moving Vehicular Target. In contrast, a vehicle not under a Motion counter will begin ITS MPh as a Stopped, non-Moving Vehicular Target. 


From the foregoing it should be clear that the game concepts of moving (A8.1), Moving (phasing), and Moving Vehicular Target are not synonymous. A vehicle can be Stopped, yet qualify as a Moving Vehicular Target. Conversely, a vehicle can be Non-Stopped but not qualify as a Moving Vehicular Target. Non-Stopped and Motion, while similar, are not synonymous either. The former represents a state during a unit’s MPh, that is, when a vehicle is Moving. Motion meanwhile is a kind of suspended state of movement that exists outside a unit’s MPh. When in Motion, a vehicle is paradoxically neither moving (A8.1)5 nor Moving (phasing), but is always deemed to be a Moving Vehicular Target, even to the extent of beginning ITS MPh as a Moving Vehicular Target.

A thorough grasp of the implications of each vehicle state and the distinction between moving and Moving, together with a careful perusal of the various charts, will greatly aid you in applying the correct DRM when the rubber meets the road.

Time to see how this all works in practice.

I hope you found this brief article useful. Knowing what DRM apply in a given situation is an important step toward mastery of combined-arms play. Please let me know if you spot any errors. Like you, I’m always learning. Now go read “Stop and Go Traffic!” It’s worth your time. -- jim


1. I (Chris) have taken great liberties editing this piece. Any errors that may have crept in are my own. Hopefully I have not deviated too far from Jim’s intent. You can find Jim's original text here.

2. The Advance Sequence of Play (ASOP) uses all-caps to underscore a) which unit (or group of units) is currently phasing, and b) at what stage a unit (or group of units) is in ITS MPh. A phasing unit conducts ITS MPh in three stages: START, DURING, and END. Although a unit is considered to be Moving, in the sense that it's the unit that is actively phasing, it may not actually be moving for the purposes of A8.1. With the exception of conducting a Search, any actions undertaken by a unit at the START or END of its MPh do not qualify as moving for the purposes of Defensive First Fire, despite the fact that the unit is Moving throughout ITS MPh.

3. In addition to Platoon Movement (D14.2), which allows two or three AFV to Move concurrently in Impulses, there are a number of other special cases where units may Move as a “multi-Location stack” or a “multi-hex stack,” such as Human Wave (A25.23), Cavalry Wave (A13.62), Banzai (G1.5), Convoy (D11.2), and Column (D11.52). Regardless of how many units participate in a Human Wave, for example, the Human Wave Moves as a single entity.

4. The Infantry, while Moving with the AFV, have yet to expend any MF, which means they do not satisfy the broader definition of moving. While the opposing side may declare a Defensive First Fire shot at the AFV, the Infantry may not be targeted (directly) because they are not moving for the purposes of A8.1. A question-and-answer confirms this:

A8.1 & D9.31

Q. An MMC [e.g., a squad] stacked with a stopped AFV declares an Armored Assault. The AFV starts. Does this spent MP allow enemy units to Defensive First Fire at the MMC?

A. No. 

5. Technically there is a fleeting moment at the END of ITS MPh (ASOP Step 3.41A) where a vehicle is moving for purposes of Defensive First Fire. Because a vehicle must either expend a Stop MP or place a Motion counter at the END of ITS MPh, the opposing player is entitled to Defensive First Fire before another unit begins ITS MPh.