Campaign tactics - zone breakthroughs and deployments

[broadsword]

If there's no "breakthrough" deployment rule in Cassino, how does Cassino handle it when the attacker enters a new zone?

Rule 8.2 Target Area of Cassino Campaign game:

"When a player gives a battalion or support unit an attack order, he also specifies one enemy-controlled area which that battalion or support unit will attack... It may not enter or fire upon any hexes of any other area".

Hmmm...That would seem to guarantee limited success for attackers in Cassino, and no way to exploit gains within a single day. But it makes sense in terms of the Italian campaign, where troops always attacked uphill and it was a slow, bitter fight.