Retreating.

[ShadowHAwk]

Since retreating states that all units should retreat to the zone where at least 1 unit came from could you abuse this rule to move through enemy forces.

For example.
German fleet is in SZ 7. UK fleet is in SZ8. can i then fly a plane through SZ 1 ( got a carriesr so it fits ) then attack SZ8 and retreat back to SZ1. My fighter came from SZ1 but this feels like cheating.

[Erwin E. Rommel]

I´ll explain it using box rules.
You can´t do this turn because you can retreat only into a territory where at least one sea or land unit came from, planes aren´t counting in this case, they are retreated separately.
But still you could do this if you had a tranny in SZ1 and would use it for attack.

[Sankt Hallvard]

Rommel's got that right. It's the same for LHTR:

Land Combat:

Move all attacking land units in that combat to a single adjacent friendly territory from which at least one of the attacking units (excluding air units) entered. All such units must retreat together to the same territory, regardless of where they came from. (See notes below for air units and amphibious assaults.)

Sea Combat:

Move all attacking sea units in that combat to a single adjacent friendly sea zone* and from which at least one of the attacking units (excluding air units) entered. All such sea units must retreat together to the same sea zone, regardless of where they came from. (See notes below for air units, amphibious assaults, and submarines.)

[Atlantikwall]

Airforce does not "retreat" at all. If you retreat your combined navy & aerial attack, "airforce" remains in that embattled sea zone untill ncm where they eventually are flown/landed anywhere else!

[Erwin E. Rommel]

Airforce does retreat, else it would fight until the battle is over. It just doesn´t retreat like naval- or landunits. 

[Atlantikwall]

I think it`s better to say it is "removed" from battle than to say "retreat" (which implies movement) as actually a fgt could even stay in the same sea zone if an acc is built there! So in the cm-phase it just stays there ("in the air" above a seazone) and (eventually) only moves in ncm.