The only terrain that is truly controlled is the terrain on which you stand. The law of the bayonet says that the man with the bullet wins. Cluster bombing from B52's and C-130's is very accurate the bombs always hit the ground. Perfect plans aren't. The easy way generally gets you killed.
Armored vehicles are bullet magnets, moving foxholes that attract attention.
If you are short of everything except the enemy, you are in combat. No plan survives the first few seconds of combat. Ammo is cheap, your life isn't. If you can't see the enemy, he still may be able to see you. Final protective fire doesn't.