So… a bit of reading today brought about a point of interest… Apparently around the time of World War I, Germany did some pretty cool things in preparation prior to the war. When I say pretty cool, I mean that they were being smart.
What they did was to go around to different parts of the countryside of the places that they were planning to invade, and bought things like farms and stuff in strategic places. They then would lay down a foundation at those farms, and erect a lightweight structure such as a barn or whatever.
Once they had enough of these set up, the invasion began. It then became very easy for them to simply tear down the structure and all of a sudden they had a strong foundation on which to place their heavy artillery. They became easily defendable firebases for their offensive.