Now that you mention it, I've always had a hankering for one of these:



Sorry, JJG - just busting your chops. I think the word you were looking for was 'coup':

coup |ko͞o|
noun (pl. coups |ko͞oz| )
1 (also coup d'état) a sudden, violent, and illegal seizure of power from a government: he was overthrown in an army coup.

And that actually doesn't apply, as the event you seem to be describing has been brewing for some time, does not involve fisticuffs, and is fully within the rights of those acquiring said power.