If you take the codes, you buy in the first campain two more Units. In the second level, you can push up your fighters, tac-bombers and level-bombers. You must do it in the following way: 1. take two level-bomber to bomb the cities. They will be pushed up after a few rounds up to the strength at 15. 2. bomb with your fighters and tac-bombers at all you can see at the map. They will get a strenght between 11-12. 3. the best is, if you take the codes, after every 30th turn you can upgrade your units.
DANGER: If you take these codes, let one unit alive. Save your position push out your cartridge and restart the game. Then destroy the last unit. If get the new campain, save it and start with the cartridge in the game new.
"I get in the 4th campain (Lower Countries) Jets, Tigers, Panthers and so on."