In NWOL, units are permitted to move diagonally on the strategic map. When they do so, they are moving past two squares adjacent to their current square, and enemy units in that square are permitted to attempt to intercept their movement, because the marching unit may have to pass briefly through one of the adjacent square to reach its destination. For example, if the situation is:
and the friendly unit at A1-S1 attempts to march to A2-S2, then either the enemy unit at A2-S1 or the one at A1-S2, but not both, may be able to intercept the movement. If this happens, then the marching unit will be redirected to the strategic square of the enemy unit that intercepts it. It will attempt to continue its move to A2-S2 (which will no longer be diagonal) on the following strategic phase (unless it is intercepted in the last movement phase).
Which unit can intercept, and whether the interception takes place or not, depends on the locations of the units. Consider placing the four tactical maps of A1-S1, A2-S1, A1-S2, and A2-S2 together as follows:
where FU wants to march from A1-S1 to A2-S2, and get to the square marked X.
It must get past unit EU in A2-S2 to do it. So the rule is: If EU is in the
upper-right corner (meaning north of tactical row 7 and east of tactical column
7) in A1-S2, then FU has to enter A1-S2. It can then try to continue its
strategic movement to A2-S2. If EU is not in position to block that move, then
FU will reach A2-S2 - otherwise, not.
FU can attempt to evade EU either by setting its entry square carefully (for example, entering at 13-0) or by using tactical movement if the commander is fairly
sure that it will be diverted to A1-S2.
An enemy unit in A2-S1 can also interrupt the movement if it is located in
the lower left corner of A2-S1 (south of tactical row 7, west of tactical column
7). Which of the two enemy units can intercept the movement depends on the
location of the friendly unit in A1-S1. Consider a line connecting 0-0 to 14-14,
that is, a diagonal line across the square in the direction of FUs march. If the
unit is northeast of this line, then it can be intercepted by a unit in A2-S1
(the square to the east) but not by one in A1-S2. This is because it's path to
A2-S2 will take it across the east edge of A1-S1, not the south edge. If the
unit is southwest of that line, then it can be intercepted in A1-S2 (the square
south, which its march to the southeast crosses) but not in A2-S1. If the unit
is in a square along the line 0-0 to 14-14, then it cannot be intercepted in
either place and its diagonal move will always succeed.