Fortifications are not a great deal of use really. They cannot move, so if the enemy go North and you have forted up South, they are out of the game from the start. Smoke blinds them and they cannot move to adjust. So the only fortifications I ever use are the MG pits with
360 degree fields of fire, as a backup for infantry positions. Fortifications are really only of use in
scenarios - where the designer can happily "go Maginot" with them
!
Buy mines and dragon's teeth. Set the dragons teeth up to
channel the enemy AI into a designed kill zone by leaving gaps in the D/T belt where you have set up QRF "gold spots" and some mines, and have units covering with
flanking fire while shielded by a town wood or hill from any frontal fire.
Andy