Answer is MINES. Dont use granades if you dont have to, also do not upgrade Stromtrooper (Stg 44 is OK but 100ammo is too much, you can place 3 mines for that cost).
I really dont wanna give you detail explanation how i did it, but i give you advice. Your ober needs lvl 1 after 3rd wave, Otto need to be near Friedrich to save his ass when rush comes in. Place mines only after fist wave. Great mines spot are next to scaffhold, upper entrance on left and after bombardment place 1-2 mines just to hold against wave comming from top( that path is pretty narrow so you will figure where, I am sure)
Save ammo for 4th wave to kill elites (at least 120-130 ammo) use smoke when Friedrich is about to die or to get those elites.

I hope that helps ;)

well... did help for me

after artillery strike you have enough time to place 2 minefields. Also try to save that smoke granade to cover friedrich if ♥♥♥♥ gets real.

I feel so proud I just completed this teaser!

I used the guy with the mg and put him on the tall wooden board overlooking the rest of the area. he can easily solo that entire side by himself. You can usually hold the other side's attackers with mines and grenades.

It takes a few tries to win at this, just keep trying and don't give up!

where is best to plant the mines? I feel that 30 ammo to kill 2 soldiers is a bit expensive.

Plz I need help beating wave after artillery attack!! 4 tries still no win! :(