Hi. Thanks for the reply.
You agree with my opponent! I'll explain why I disagree...I'd be grateful for more views.
When a fortification marker is breached the following applies (a)
(a) "When an area fortified by a fortification marker is breached, remove the marker; that fortification’s effects on all its border segments are nullified. No breach tokens are placed."
So as I see it, when the thunderhawks attack a fortification marker you treat the attack on the border as a breach...therefore you treat it as specified in (a) but without actually removing the marker.
Does anyone know if these questions ever get on the FAQ?