What exactly happened to get the Mages Guild Disbanded?

I see bits of text saying that the College of Winterhold was not affected by the disbanding of the Mages Guild.

But what is the story of the disbanding of the Mages Guild? What happened? Why was it disbanded? (For example, did they do something treasonous? And if so, what was it?)

They were in-part blamed for the Oblivion Crisis, which caused havoc all over Cyrodiil. Of course they didnt have anything to do with it but the people had to blame somebody.

Mages' Guild got partly blamed for the oblivion crisis. The man who started the Mages' guild Vanus Galerion was also against necromancy. So that was not the reason for it disbanding. But when Hannibal stood against it... the mages' guild got a lot of enemies that wanted to tear it down. Also inner conflict happened in the guild after the oblivion crisis. So the guild exists still.. but now has two different organisations, with less influence.