fall back foxholes?

[Extraordinarius]

And I had been starting to think I would only have craters and purchased trenches to put my units in!

Just to make sure, you do realize that every defending infantry unit or gun in an 'Attack' or 'Assault' starts in a foxhole by default? If you hit the 'Dig in' command during deployment, that foxhole will disappear, but it will reappear if you hit 'Dig in' again. Unfortunately, the foxholes are mostly concealed by the colored base, but you can see them if you view them at level 1 or 2. In one of the first attacks I played, my opponent finished his setup by clicking through his troops one at a time and commanding 'Dig in', thereby removing every entrenchment. In an 'Assault' you get a number of fallback foxholes equal to the number you got with the purchased units.