Pretty much an entire country once broke away: it was Taiwan, I think. This was reported in the WTS literature. I remember reading about it in a yearbook, back when the yearbooks, for a particular year, focused on the history of the org in just a few countries. The incident occurred years ago, back in the days of one branch servant. The guy had some falling out with Knorr and Franz, or maybe it was JFR? They "removed" him but most of the country went with the guy, not with the org. For years afterward, "growth was very slow there," to quote the official line. The guy had poisoned the well for the org. Eventually the org recovered, of course, but it took many years to do so.
If someone here has the yearbooks in their library, perhaps they can find the story by finding out which year has the history of Taiwan in it. Today they would never relate the story (or likely put the ybs online or on a CD), but I remember reading it in a old yb. That yb dates to sometime after the late 50s or early 60s. Back then they gave a short blurb on each country. If I remember correctly, it was a yb from the 1970s (but I might be wrong here). I think it was in the late 60s or early 70s when they began the yb format of focusing on the history of just a few countries each year. They used to give quite a history. I imagine when they came out with Proclaimers book, those ybs were a major source of info for it. The Proclaimers book, however, nowhere mentions the Taiwan break-away like the older yb did.
If someone could find this yb, I'd appreciate knowing the year.