WOW! I selected the mission on Normal difficulty and the mission is SO much easier. I could now do airstrikes and it wipes out everything just like the coastal gun. However, I never did find any antitank mines. I did find AP-40 granades, but no mines
Now my problem is this, how do I change the difficulty in my campaign? I changed it to Normal in my profile settings, but when I go to load the mission it remains in Easy mode (no airstrike). Can you switch mid-campaign?