I did notice that the rhythm changed a bit in the third verse, but I didn't think it mattered that much. But if you wanted, it might sound better like this:
All around the thunder rolled,
A voice screaming out its fury,
But I would not move a single inch,
While echoes shook the empty world.
But then again, I've completely butchered your verse, and that might not have been what you were trying to say at all, so feel free not to use it. ;P
Also, the first verse -
I stood upon the sodden earth,
The rain kept pelting down,
But I refused to move my bare feet,
From where they were planted on the ground.
This is good, but the second line seems a little abrupt. I think you need two or three more syllables in there somewhere. And the thrid line has one syllable too many.
Maybe -
I stood upon the sodden earth,
The rain kept pelting down upon me,
But I refused to move an inch,
My bare feet planted on the ground.
But I think your poem is just fine as it is. :nod: (In fact, it's brilliant as it is ;P ). So don't feel that you need to change it or anything. It still has rhythm and flow as it is.
Edit: On second thought, the first verse is fine. I was just reading it strangely. ;P