Slitherine

Because your units got heroes and experience in Spain its difficult to NOT kill the bad guys in scenario 1 of 1939 (in doing you loose the Commedation things or whatever) so if you have heroes maybe unhero them or attack in such a fashion ya take losses or something I probably go impatient but having played it also by starting with 1939 ... and not playing Spain Axis op first ... it was easier to not destroy units.

But since everyone has played 1939 1000 times this thread is pointless ...

You dont have to fight at all. Go for the alternate path, capture all secundary cities and just ignore or surround the enemies, so that they cant do anything.
It is one of the most important scenarios, if you lose some of your points you wont get Kercher Superhero in the next scenario.

Yes go for the Alternative goal.
Most of the enemy units retreat, after the first or second attack, so you can capture the vic hex.
Let the unit stand in the vic hex and only defend the hex. At some vic hexes it's a good idea to get a arty in position for support attacks or small attacks, so the enemy refresh their units instead of attacking.