Units can retreat or rout out of the battle square if they fail
a morale check. The units of the winning side can rout or retreat
also, though it is less likely. Units can rout or retreat in
either the firing phase or the melee phase.
A unit which retreats must make a tactical move of 1 to 4
tactical squares away from the battle. If a unit moved into
combat, it cannot retreat in the direction it was moving, nor one
direction to either side. For example, a unit which moved north
into battle cannot retreat to the north, northeast, or northwest.
These forbidden retreat directions are called invalid. If an enemy
unit moved into the combat, then the retreating unit cannot
retreat in the direction from which the enemy unit came, nor one
to either side; those directions are also invalid. For example, if
an enemy unit entered the combat from the east, then the
retreating unit may not retreat to the east, northeast, or
southeast. A retreating unit will select from among its valid
retreat directions. If there are adjacent enemy or neutral units
in an otherwise valid direction, it will not retreat in their
directions (although it may select a direction which would require
retreating diagonally past the adjacent unit even though that
retreat move will fail). If there are adjacent friendly units in a
valid retreat direction, not in the same square as enemy units,
then it will retreat in one their directions. The unit will
shatter if it has no valid retreat direction, or if its retreat
move fails for any reason, including block by an enemy unit.
A unit which routs must make a strategic move to an adjacent
strategic square, which is selected at random. If it has no valid
retreat direction, it shatters. Units cannot rout in invalid
directions (as defined in the previous paragraph). Invalid
directions will not be selected randomly; but units in which a
strategic move is blocked for other reasons (such as an enemy unit
in the exit cone, or requiring a river or mountain crossing) may
be selected, and will result in the unit shattering.
If a unit on the losing side has neither routed nor retreated, and thus is still in the battle tactical square at the end of the battle, then it must fall back. It will fall back exactly one tactical square, and will choose a direction using the same criteria as retreating units choose directions. Units which cannot fall back, either because they have no valid fallback direction or because their fallback move is blocked, will shatter. A unit which needs to fall back may be unable to do so if enemy units have surrounded it in the melee, even if it had a valid retreat direction. In this case the unit is trapped and will shatter.
The following messages are printed as a result of movement from routing, retreating, or falling back:
"US1IN is unable to move." - This means a unit had to retreat or fall back, but its movement was blocked in the first tactical square it tried to move to.
"US1IN is unable to rout/retreat/fall back and is forced to surrender!" - This means a unit that had to rout/retreat/fall back had no valid direction in which to move.
"US1IN is exhausted, and surrenders!" - This means a unit lost a
melee and had fatigue of 16 or greater.
"CSIN is unable to rout and is shattered!" - This means a unit
had a valid rout direction, but its attempt to move in that
direction was unsuccessful.
"CS1IN is trapped by enemy forces and surrenders!" - This means that a unit lost a melee but was so entangled with the enemy units that it was unable to leave its present tactical square, even if it had a valid fall back direction available. The odds of this happening are higher if the unit had a flank turned (higher still if both flanks are turned) but it can happen even if not. This message is printed only for units falling back, not for those that failed morale checks and are retreating or routing.
"CS1IN tries to rout/retreat/fall back but is blocked, and surrenders!" - This means a unit tried to rout/retreat/fall back after combat, but all the squares to which it could legitimately move were impassible terrain, or contained enemy or neutral units, or in the case of rout, were invalid strategic moves.
"CS1IN has no direction to retreat and is forced to surrender!" -
This means that all valid directions in which a unit could retreat
were blocked by hostile units.
Note that in all of these cases, although the program says
"surrender" the unit will actually shatter, though it will lose
many prisoners in the process. Updating the code is on the wish
list.
Updated 2-22-22