temporary fortification meaning in English

临时性防御工事

Many years ago the spring induced the natives to select the place for their temporary fortification .
很多年前，这眼清泉，使得土人们选中这儿作为临时筑堡设防的地方。
Mechanized armies and riders do not have this temporary fortification parameter since they already have “ fortification ” and “ assaulting ” . generally , in the temporary fortification , archers are better than riders and riflemen
我想投石机等单位应该可以摧毁这种临时的工事。这一条是我自己加的，不好就请去掉。