The moat can greatly hinder troop movement. Moat can be placed in the same manner as tiled buildings or constructs, covering a 2x2 area under the cursor and built instantly when done. It requires gold to place, proportional to the size of the covered area. Moat cannot be sited while enemy units are present.
When sieging, hostile units can fill in the moat, creating sandy terrain in their wake. All ground units except for horse archers, hobilars and mounted knights can fill in, without the danger of drowning.
Using defensive construction such as cats or mantlets should be used for covering digging units.
The great gatehouse comes with a drawbridge, which can create a controllable passage for the owner's units and citizens.