

The Images:
Front (first) image:
The Setup: The castle (on the little “island” of land, as seen on the inset map above) and gatehouse were built to protect the low part of the plateau where access to the main plateau could be easily gained (the main plateau being where most folks lived). On the plateau itself were several canals to direct water to the main reservoir or to the guard castle.
The Story: An enemy army sneaks into catapult range under cover of darkness (their view is basically that of the top-right section of the back/second image). As dawn breaks, the castle guards are caught unawares by the army below and go to rouse the castle. Meanwhile, the army fires their first volley, which strikes low on the large rounded building. What they don't know is that the lower half of this building — along with quite a bit hidden by the land it's built upon — acts as the main reservoir for the castle. The struck wall buckles and falls, along with the land in front of it (which had been weakened over the years by small leaks in the reservoir), in a massive mudslide which sweeps the attacking army away :)