That was pretty nice.
I liked the backgrounds. It's interesting to see cloth as mountains/hills. It's a welcomed change of pace and it shows that you're not afraid of going slightly outside the bounds of the 'brick world.'

There are a couple of things that I think would really help your films in the future:
If the enemy tank fires on the defending army and the shell impacts on the ground near the tank...the dirt/environment at the point of impact should show evidence of impact. A pothole, dirt flying up, etc....but in brick form.
Tanks are big, heavy hulking machines. When they travel, almost all tanks leave some kind of tracks and the treads tear up the ground underneath. Showing 'Lego tracks' behind the tank or to the sides would give your animation that extra boost of believability.

Thanks for sharing.