Nullum gratuitum prandium.
On page 16 of the first edition printing of the rules booklet under this topic it states the following:
You must consult the casualty roll results table at two increments lower than what you naturally rolled.
For clarification: when I invade a barren wasteland and roll a 9 on the Casualty Roll Results Table, do I...
A.) Subtract 2 from the roll and treat it as a 7: "lose invasion force only"?
B.) Drop 2 lines down on the table and treat it as a 4-5: "lose 1 additional eligible unit OR retreat"?