Official rules only, not house rules.

How and when are you allowed to retreat, both in an amphibious landing and a land battle?

The rules say that you can't retreat in an amphibious battle. What happens if the battle ends with both sides taking one casualty? Does the attacking force fall back to the transport from once it came and the defender stays put?

In a land battle, can the defender choose to have all (land and air) units retreat to an adjacent friendly/unoccupied territory? Or is the option to retreat restricted only to the attacker?