OK, I'll have a shot at explaining. But first - yes, using the trench and the view 'over the step' was a grand idea.

Animal Farm was a swipe at Communism by George Orwell, and in this the pigs led a revolt which resulted in an animal-owned farm; eventually they themselves became an elite, and things ended up same as before for the other animals.
In this case, some years down the line the Pigs are at war with their neighbours, and they're into mechanized warfare (hence the SU with the - uh - sawn-off cannon); and four of the bosses are meeting to plan the next campaign (on what I'd love to have for a games table!). The tank happened to be passing; and there's a human mechanic (his tools in his apron can only just be seen) for no good reason except that he has slightly porcine features, which can of course not be made out in my photo. With him is a cat. Cats belong anywhere.
The pig is in the tank because I like tanks with a Saukopf...

The four 'main' pigs are, by the way, allegoric: one is a War pig, one a Worker pig, one a Sea pig and one an Air pig (hence the propeller leaning against the table). Yes, I know, hopelessly over the top and whatever happened to the-picture-tells-a-story?
But they were fun to paint. And I'd had this table idea for ages, so this provided a good excuse to use it.
WireLizard - yes, the table is a map tile from GW's Mighty Empires campaign pack (the current edition) - it was free with an old White Dwarf; the pigs are actually mounts for a range of dwarfs from -dang! I forgot! I'll try to find out.