Very nice. I like the little details, for example the left side door hanging open over the flooded shell crater. That's possibly the worst place I could imagine having to bail out of a tank, seeing as there's no guarantee you could even climb out (and thats assuming you didn't drown). It really emphasises the vulnerability of the vehicles.
I was going to suggest some fallen soldiers in and around the trenches, but looking at it now, I think the tank's isolation creates a nice sense of abandonment. The war has moved on, but the lumbing beast remains, fallen and forgotten. Nice work.