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Another "Back to Basics", today we're looking at the concept of "Escorting".
Units that are Falling Back are automatically removed from the table if any model in the unit hits the board edge or at the end of the game. This makes them easy Kill Points and unable to Score or Contest objectives. Also, a unit that is Falling Back counts as having moved that turn and can't use Heavy Weapons, even if they Regroup. There's exceptions, of course, such as Space Marines that Regroup using "And They Shall Know No Fear" and/or anyone able to move and fire Heavy Weapons. Still, these are categorically "Good Things" when it is happening to your opponent. So once you've gone through the laborious process of breaking an enemy unit, don't you want them to stay broken?
Units can take a Regroup check at the beginning of the unit's Movement phase. If they pass the test, they regroup and hang around. If they fail, they run another 2d6" or more. Simple enough. The problem here is that you're relying on luck of the dice when odds are probably in their favor. Many units, such as Space Marines, don't even have to test and automatically Regroup. But there's a simple solution: never allow them to test in the first place!
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There's three criteria that must be met before a unit can test to Regroup. If any one is failed, the unit keeps on running. These are:
1. The unit is in coherency. This one is probably the most uncommon reason for a Regroup to fail. Not only will smart opponents remove casualties or move models in an order so that this doesn't happen, but many people naturally bias the movement angles and/or distance moved to keep the unit in coherency. As you've already Broken one of their units, getting picky about this with an opponent is a sure way to kill the fun of their game. There are certainly ways to create this occurrence with some really tricky tactical use of another unit, for an opponent to get unlucky on a unit with weird wound allocation, or even for them to make a stupid mistake when moving their models. But these aren't occurrences I'd suggest relying on.
2. The unit is at or above half strength. Just killed off 1/2 those guys and made them run? Great! You can ignore them now as they'll keep running. Well, unless they're Eldar with an Avatar near, IG with Orders, Marines with "And They Shall Know No Fear"... the list just goes on and on. Almost every Codex has some way of getting around this requirement or won't break in the first place. So be aware of what your opponent's army can do before you rely on this one.
3. There's no enemy unit(s) within 6". This is the key to Escorting and the most common reason for a Regroup to be skipped. Why? Because it is a factor that YOU can control. As long as there's an enemy within 6", even the bravest Space Marine will keep "Advancing to the Rear".
As with all things, there's a catch. I've been asked "Units that are Falling Back can still shoot! Why would I want my guys to Escort and get shot up?" It comes down to one thing: Tactical
Opportunity-Cost. You need to honestly assess the amount of damage that unit will cause to your forces before they are removed from the table. Also look at secondary factors like if pursuing them will put your unit out of position, open to other fire or otherwise at a disadvantage.
Then compare that to the amount of damage the enemy unit would be able to cause if allowed to regroup. Given that the unit will be under your opponent's control, looking to cause maximum havoc, and able to Score or Contest objectives? The majority of the time you will want to keep them running.
But wait! There's ways you can minimize the amount of headache the broken unit causes you. My personal favorite? Don't make Escorting your primary objective. Instead, look to accomplish another tactical objective AND Escort the enemy. For example, this can include charging other enemy units (this usually protects you as the Broken unit cannot shoot into CC), securing a mission objective, shooting up another target, Screening, or even just annoying your opponent in hopes that it causes them to make a mistake. How can you do this? Here's an example where some Genestealers have found themselves in charge range of the Red Squad of Space Marines... and then charge on in.
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The Marines killed one Genestealer but lost three of their number, fail Morale and Fall Back, aren't caught on a Sweeping Advance, and move 9".
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So what do you do now? I've seen many players just move their entire unit back into the ruins and spread out to avoid enemy Blast markers. But is this really worth it? Those Marines are probably just going to regroup, walk back up and shoot you anyways. They're also going to get extra attacks if they opt to charge. Worse yet, your opponent might not play your game and have the unit wander off to support somewhere else! So why not move up a few guys and keep them running? The majority of the squad is still in cover and you've lost nothing tactically by moving up. Yes the unit is going to get shot by both squads, but they were going to be shot anyways. Now when the Red Squad checks for Regroup, there's enemy units within 6" again and they will Fall Back. This can potentially put the Red Squad out of Rapid Fire range, their move direction isn't optional, and they won't be able to assault!
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But that's not the end of it... say the Red Squad only falls Back another 6" on their turn. This puts them out of your unit's range, so they will Regroup on their next turn. So why not move in such a way that you prevent this?
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Then when you charge, you will have models within 6" even if the combat is a press. On your opponent's turn, that squad will hit the edge of the board and be out of the game.
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Now remember, these Fall Back moves (and Regroup checks) happen at the start of the owning player's Movement Phase. The average Fall Back distance is going to be 7". With a 6" move and the option to Run or Assault, a unit should normally have no problems keeping up with a fleeing enemy and forcing them off the board.
UPDATE:
sonsoftaurus brings up an excellent point that Transport vehicles are a great unit to use for this purpose. They are fast enough to keep up, can Tank Shock to cause extra Fall Backs, and might as well be doing something anyways. It's a great use of a Rhino or other vehicle that's hanging around.
ChimeraHiveMind also notes a very important side effect of Falling Back: "Troops who are falling back automatically fail all Morale checks, except those to regroup." Subsequent Morale checks from Shooting, Tank Shock, Psychic Powers or otherwise can cause the unit to execute additional Fall Back moves. This can be used to push a unit multiple times in the same turn and cause them to quit the field even sooner. Learn this, know it, love it.
Cheers and hope you've learned something! For my part, it was so difficult to write this entire thing and not make any "Sisters of Battle Escort Service" jokes... "Get thee to a nunnery!" Heh.
***Images from Motor Trend, July 1990 and Monty Python's Holy Grail. Used without permission and will be removed upon request.***