Using ''Trenches''

I have noticed that on several maps there are many geographical features that can be used like trenches. For example, on Prussian Hills I always fortify the bottom left corner of the map(where that mini-hill is and a road) and the road seems to deflect bullets and protect my infantry. Also on Waterloo, there is a road running from the center house that can be used for the same purpose(I killed about 70 enemy troops with 20 casualties using this). However one possible issue is cavalry charges. I'm not sure if my opponent simply circumvented them, but stakes seem not to work when planted inside them. I want to ask if anybody else has noticed this,and how you can use it properly.

I've noticed this as well, and usually try to take advantage of it, although the micro involved is taxing to make sure they don't just shoot the ground in front of them.

As for the one at Prussian Hills, I didnt have to do anything. The one at waterloo on the other hand, I move them slightly in front of it so they can be in cover while firing at the same time. Have you ever used artillery on it?