ASL Academy recently did a video covering a routing example first posted on Facebook. The situation discussed was from a game played by Philippe Vaillant, with many layers, and I would like to discuss it here in this article. I think it highlights some routing subtleties that demonstrate just how little control players have over routing units.
The Situation
The original example image is posted at right. As originally described, it is the American rout phase, and the broken unit must rout because it is Adjacent to a Known Enemy Unit (KEU). Per A10.51, a broken unit MUST move to the nearest building or woods hex. Calculations on “nearest” are measured in Movement Factors (MF) spent reaching the destination, not merely counting hexes to the target. There are also some caveats on known minefields, FFE, and other reasons not applicable to this discussion. As depicted, the 4-4-7 is out of the broken unit’s LOS and thus not a KEU. The closest woods hex (in MF) is P5, two MFs away. Remember, the unit can enter P5 along the road, making the “distance” two MF.
The First Clarification
The first clarification noted that Pine Woods (B13.8). This makes Woods terrain 1.5 MF and a level 2 LOS Obstacle. Fortunately, this changed nothing. In the YouTube video, it was noted in the comments that Light Woods (B35) were in effect. If so, this would change everything. Light woods are not an LOS Obstacle; they are a +2 hindrance. This change means the 4-4-7 IS a KEU at the beginning of the Rout Phase and means P5 is not a valid rout destination. For continued discussion, I will consider the example of Pine Woods and P5 to be the rout destination.
Applicable Rules
The A10.51 rule is all we need here, but it is dense and complicated. Let me quote the rule and take it apart piece by piece: … Assuming it can abide by the previous requirements, a routing unit must move to the nearest (in MF calculated at the start of its RtPh) building or woods hex (even if overstacked) unless that route is through/into a known minefield or FFE, or is not traversable (e.g., through a Blaze, unbridged Water Obstacle, Cliff, etc.). As long as it reaches that hex during a single RtPh, it need not use the shortest route, but as long as it follows the shortest path in MF otherwise, it may enter a shellhole/entrenchment/pillbox to avoid Interdiction even if it can no longer reach that woods/building hex in a single RtPh. … I have trimmed the rule down to focus on the parts applicable to this article.
A routing unit MUST:
- Rout to the closest building/woods
- Can take a longer path IF (and only if)
- It reaches its rout destination
- Moved into and out of Shellholes/Foxholes, but is otherwise on the shortest path
Now, go back to the Example and apply these rules. The Broken unit MUST rout to P5. It can rout there via Q6, but that is Interdicted by the unit in P4. Some clever players think to just take the longer path via B7 (B7 (3MF), B6, Q6, P5). Once the unit gets to B7, it gains LOS to the 4-4-7 in P4 and can pick a new rout destination. But go back to the bullet points. If a unit opts to take a longer rout path, it MUST reach its rout destination. Once the unit reaches B7, it can no longer reach its rout destination. The path is not a legal rout path. The same applies if the broken unit tries to rout via B6. Neither rout option is legal, and thus there is no rout path free of Interdiction, and the unit must Surrender via the Rout Phase Method to the unit in P7 or be Eliminated for failure to rout.
The Second Clarification
Phillippe later revealed the 4-4-7 was Pinned. This changes the outcome. Pinned units cannot Interdict. The longer rout paths remain illegal for all the same reasons. This time, when the broken unit routs to Q6, it is not Interdicted but MUST choose a new rout destination to rout to. Both C5 and B7 are valid choices as both are 2.5 MF away (remember, “closest” is determined by MF, not hexes). The Broken unit can ignore B7 if it wishes. When the Broken unit is choosing a new destination in Q6, it is two hexes away from P7. Hex B7 is also two hexes away and is ignorable (although still an option). Note that we changed to measuring in hexes for this purpose.
Getting More Complex
I have modified the situation again. I have removed the Pin counter but placed Shellholes in Q6. This again significantly changes the outcome. The rout destination remains P5. The Broken unit still cannot take the longer rout paths via B6 or B7 for all the same reasons. However, the unit can now move to Q6 via the Shellholes for 2 MF. Even though it can no longer reach the P5 destination, it is STILL on the SHORTEST path and able to redirect to a new rout destination. Again, C6 and B7 are possible destinations. Hex B7 can be ignored at the routing unit’s option. Routing to B7/C6 is done via B6. Is B6 Interdicted?
Rule A10.53 states that a routing unit that enters Open Ground in both the LOS and normal range of a unit capable of placing at least one Firepower on that hex without any form of DRM is Interdicted. Rule A10.531 further defines Open Ground as any hex in which a theoretical First Fire attack would apply a -1 FFMO DRM. Finally, referring to B10.31, a unit receiving fire from a lower elevation is entitled to a +1 DRM for Height Advantage (HA) EXCEPT in the case where the Line of Fire (LOF) crosses the Crest Line through the same hexside intersected by the LOF. In this case, when the unit leaves the Shellhole and goes to higher terrain in B6, it crosses the Q6/B6 hexside, the same hexside the LOF crosses when traced to the center dot of B6. Since the unit is not entitled to a +1 DRM for HA, it instead receives a -1 DRM for FFMO and is subject to Interdiction.
Since it is subject to Interdiction in B6, would it Surrender instead, just like before? In this case, no, it does not. The unit has a safe rout path free from Interdiction if it just stays in Q6. Since it has a free rout path, the Broken unit can opt to risk Interdiction in B6 and continue on to B7/C6. Without knowing or specifying the victory conditions, I cannot say which is the better call, so I will refrain from doing so here.
Conclusion
There are times and places when players may choose between options when routing, but there aren’t as many as some players seem to think there are based on responses to both the post and the video. Specifically, a routing unit may only take a longer path to its rout destination under very specific conditions, and if those conditions are not met, that routing path isn’t legal. If a routing unit cannot reach its rout destination via a longer path, even if that reason is a newly discovered enemy unit, that path is not a valid rout path. A unit can only choose a new rout destination if it is otherwise on the shortest rout path, calculated in MF, to its current rout destination. If it is on ANY other path, it must begin to rout again and choose another path.
I hope this helps people better understand this interesting and complex rout example. Thanks to Phillippe for posting it. It was fun to watch all the answers and think about it all here.
— jim
GET TO THE CHOPPA…!!! 
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This article was originally published June 16, 2025 (v1.0).
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At the start of its RtPh, a routing unit must designate its destination and must ATTEMPT
to reach it during that RtPh [EXC: if using Low Crawl]. If a newly-Known
enemy unit prevents this, a new destination is re-figured from that point.
This is true if you are otherwise on the shortest path. A routing unit can only take the longer path in two instances: the unit reaches its route destination, or if the unit is otherwise on the shortest path, it cannot reach its destination if it is spending MF to enter/exit Shellholes or Foxholes.
If you are not on the shortest path and a newly revealed unit prevents the rout from reaching its destination, you start over again until you find a legal rout path, cannot find a legal path and Surrender, or your opponent misses your mistake and you both play incorrectly. For the third option, there is A.2.
Thankyou Jim.
I appreciate your careful and clear work here and I did learn some stuff!
In your answer to Stu (Rout Better) above when you say “start over” do you mean that the routing unit(s) is taken back to the hex it started its Rout Phase from and begins it’s rout again?
I suppose if you want to be 100% rules compliant, you would move them to the last legally entered Location. In the case of the rout presented in the YouTube video–which I think Stew is referring to–it would be a start over.
Having said that, there is nothing gained by simply starting over. The game is hard enough to play without sitting around and playing “gotchca” with each other. Routing is programmed perhaps more than anything else in ASL. The final answer is almost always a 1 of 1 or a 1 of 2 answer. Working together to get to the right answer isn’t a bad thing.
Thanks Jim. Appreciate the follow up.
Thanks, Jim. I learnt a lot about routing from the discussion on Facebook with the other posters, and even more from your in-depth insight here.
Three MF, not four (double COT) to move into B7?
Pine woods entry cost is 1.5M MF. When double for higher terrain it becomes 3 MF.
Jim, I’m wondering if there is something to be learned by adding another example into this routing situation, and that is when the 447 is concealed at the start of the rout phase, and decides to reveal itselt during the rout of the broken unit, both when it routs via the shortest available path, as well as (and perhaps more interestingly) tries to rout via a longer path (if this is allowable). AS always, thanks for your efforts in exploring the nuances.
If it were concealed, the outcome would depend on when the 4-4-7 were revealed and the path taken. If rout path was through B6/B7, and revealed when the routing unit got there, nothing changes. The unit is not in the shortest rout path, it cannot reach its intended destination, it must return to the most recently, legally entered Location.
Suppose the 4-4-7 isn’t revealed until the unit enters P5. If the rout path were B7 (3), B6 (1), Q6 (1), P5 (1), the routing unit has exhausted all of its MF for rout and ended its rout Adjacent to a now known enemy unit and would be eliminated for failure to rout. If instead, the routing unit routed via B6, Q6, P5, it would have spent 4 MF routing. The 4-4-7 drops concealment when in P5. The unit must continue to rout with its 2 remaining MF. Hex O6 is the new destination (remember, it still knows about the enemy unit in P7 but isn’t getting closer). If the trail continues past O6, the unit could potentially rout one more hex after O6 as longs as the “next” Location is a Building or Woods hex.
For all the other rout paths I can think of, if the 4-4-7 is revealed BEFORE reaching P5, the information relayed above remains the same. There may be an edge case I am not aware of so use what you know if something like that comes up in your games.
I have a mini-question on P5 that may be irrelevant in the present situtation but could matter in others. I’m not on Facebook, so I don’t know if it was discussed there already.
P5 is a woods-road hex (B13.31). If a unit enters it via the road depiction, it won’t be eligible for the woods TEM against enemies firing on it with a LOS to it that does not cross the woods depiction.
Effectively, the routing unit on the road would be in OG from the perspective of these enemies.
That raises a more general question. OG is not a legal rout destination. A road in a woods-road hex is sometimes but not always OG.
So, is the road in a woods-road hex an illegal rout destination some of the time, or all of the time?
Is it legal as long as no enemy is present that can shoot into the road without TEM? Or is it actually never legal?
Of course the solution in the current situation would be somply to enter the woods portion of P5. But that may not be possible on other occasions.
It is legal regardless, the only question is whether the open ground forces an Interdiction DR and if that Interdiction would result in Surrender instead.
Sorry to ask, but there is something I definetly don’t understand. Moving to B6 costs only 2MP, so why the broken unit cannot take that way to rout?
If a unit takes a longer rout to its destination it must either reach the destination or be moving along the shortest rout, enter and exiting Foxholes. Once the unit moves to B6, it can no longer reach its destination and it isn’t on the shortest path hence B6 is not a legal rout.