In Memoir '44, if an infantry unit is surrounded by sandbags, the rules state that the unit "may ignore the first flag rolled against it." I can come up with two interpretations that seem to have very different implications of the power of a sandbagged unit:
In order to force a retreat you must roll two flags during one attack (e.g., roll two dice, get two flags, the unit retreats). Sandbagged units are nearly impossible to force a retreat without resorting to using certain tactic cards.
You can roll one flag on one turn, then on a subsequent turn you may roll another (single) flag, and this forces the sandbagged unit to retreat. Sandbagged units are still difficult to force away, but not nearly as bad as (1).
What is the correct interpretation?