"I was upset with the direction in which some people were taking the Board so I resigned."
"Well, I suppose that will show them. Of course, you'll no longer be there to voice a different opinion and they may be able to get a more pliable person named to replace you. The memory of your resignation will probably fade within a couple of weeks, if not sooner, and I bet your adversaries popped champagne at the news of your departure. But, aside from those considerations, it must have felt good to resign."