Backwards by the tail?

When I turned the horses loose to eat hay, I stopped Tug by the gate. I got his tail and applied a little pressure while I shook the halter in my hand. At first he moved his butt away, but pretty soon he couldn't turn that way because of the fence and he took a step or two backwards. I had to kind of stand in zone 4 and shake the halter up and down in zone 3. He did this three times, at Liberty too! This was the first time I've tried this, so it should be interesting when we do it online! :D