When can sea units support land battles, and vice versa?

Question

In the 1st edition rule book it is explained that ships can support an adjacent battle:

Ship units may support adjacent combat in a sea area or a ...

But what if I'm attacking from a spot that touches water, into a spot that does not touch water? The rules don't ever specify what the battle area is. It makes intuitive sense that the ships wouldn't actually be able to cross land, but since the rules don't specify the answer it has become a question for my gaming group.

This would also be the question for land units. Do the units need to be touching the defending land/sea area? Or would they be allowed to be called in from areas adjacent to the attacking land area?

Answer 1

I'm only familiar with the 2nd Edition, but I believe it's similar. (This question doesn't list include support in it's list of differences.)

When thinking about support, it doesn't matter where you're attacking from. The battle takes place in the region troops enter to attack, and only units (ships or land units) bordering the defending region can offer support to either side.

This makes sense: you can't march your troops to the border and yell taunts until the defenders come to you, you have to go to them. Hence attacks are initiated by a March order. It doesn't matter at all what regions border the region your attackers came from. Only the regions bordering the one region where combat occurs--the region being attacked--can offer support to the combat.

Regarding your last point, land units can never support a naval battle. They can't swim well enough.

I bet this was a common confusion from the 1st Edition; the 2nd Edition rules seemed to really drive both of these points home.

Answer 2

Ships may support land combat, land units may not support sea combat (my friends always say "imagine the men and horses swimming out into the sea" as opposed to ships raiding the shores).

The battle takes place in the area which you are trying to conquer, so only units adjacent to it may support it.

References:

From the rules p. 17:

Ship units may support adjacent combat in a sea area or a land area. Footmen, Knights, or Siege Engine units, however, may never provide support to combat in a sea area.

From the rules p. 13:

During the “Declare Support” step of combat, supporting units adjacent to the embattled area may add their combat strength to one of the two participants in the adjacent combat.