Didn't the provisional IRA force the government's hand in the Good Friday Agreement? There's a fairly good chance the Catholic portion of Northern Ireland, which generally favors independence, will overtake the Protestant population which generally favors union with Great Britain. The GFA allows a popular vote on the matter. So by securing a vote, NI will likely go back to Ireland in a generation or two.

There were also immediate wins, particularly dismantling the RUC which performed attacks against civilians and colluded with unionist terror groups.

(disclaimer: I believe attacking civilians is awful and god isn't real)