Fokker1138, you have the gist of the answer, so I will accept it. For those of you wanting the whole story:
The Wolverines were a tad miffed that the Council awarded a disputed Brian Cache to the Widowmakers, so they attempted to seize it for themselves and were publically censured after losing the Trial of Refusal. They challenged the ruling and made it personal with Kerensky himself, and seceded from the Clans. This is when they used the nuke, and were then slated for annihilation by the other Clans.