This chapter critically examines the origins, conduct, and aftermath of Operation Unified Protector (OUP), NATO’s 2011 mission in Libya. Few multilateral military interventions have ever been carried out as expeditiously and effectively, with NATO’s military coalition accomplishing in just seven months the operation’s objective of protecting civilians against Moammar Gaddafi’s regime. All this was done with an express mandate from the United Nations Security Council. However, inconsistencies in coalition members’ interpretations of intent and burden-sharing diminished the value of OUP in the long term. When it comes to the troubling aftermath of OUP, four failures of anticipation are examined. Two of these pertain to the lack of clear ownership of the post-conflict situation; the other two can be ascribed to insufficient attention being paid to the political context within which the intervention was designed and executed. Over a decade after the mission was launched, the negative domestic and regional repercussions continue to reverberate.