Good Friday Agreement
The deal which more or less put a stop to the Troubles, giving pretty much everyone involved a fairly shite deal but at least moving the bright paramilitaries (the 'Ra) into crime and politics and the dumb ones (the various Loyalist street gangs) back into their ghettos. The small price paid for this was the destruction of the moderate strain of NI politics with the eclipse of the UUP and the SDLP. Good enough for Tony.
Further complicated by the newly-elected and somewhat unworldly Labour Government's inability, post-1997, to get the Republicans to move along the route agreed by the Major government without even more bribes. Persons of a cynical disposition might well choose to discuss Mo Mowlam when assigning blame for this.
Immortally described by the Sainted Seamus Mallon as "Sunningdale for Slow Learners".