Advancing after combat
If the combat leaves the target hex empty of enemy land units (MiF option 6: except supply units), you can advance any of your attacking units into the hex. Defending units can never advance.
Turn an advancing unit face-down if the terrain cost of the hex exceeds the unit’s movement allowance.
If the result included a ‘B’, you may be able to advance some attacking units a second hex (unless you converted the ‘B’ into an ‘R’ result).
The first hex of the advance must be the defending hex. If the defending hex only cost 1 movement point (modified for weather), you can advance each attacking HQ-A, ARM and MECH unit a second hex. You can also advance MOT and CAV units a second hex if they start and end the advance stacked with the same HQ-A, ARM or MECH unit. Turn an advancing unit face-down if the cost of the second hex is 2 or more movement points.
(AsA/MiF/PoliF option 2: MOT and CAV corps/armies can’t advance a second hex if only stacked with a MECH or ARM division.)
You can conduct an overrun (see 11.11.6) in the second hex.
Ignore all enemy ZOCs (but not enemy land units) in an advance after combat.
[Italics original; I have omitted some original bolding.
So an ARM or MECH can move up to 2 hexes during the advance after combat stage as long as the first hex cost only 1 movement point (i.e. clear or desert hex in fine weather; maybe some other hexes if you don't play with motorised movement rates and/or you do play with railway movement).
