Fortifications, Obstacles and Cover
Many scenarios direct players to create the game board with a variety of fortification and obstacle elements. In addition, some fortification elements can be created during the game by certain unit types (such as engineer squads digging entrenchments), and some fortifications and obstacles can be created or removed by players using Operations cards provided to them by the scenario.
You only have to kick in the door and the whole rotten structure will come crashing down. (on invading the Soviet Union) 
