No small number of books laud and record the heroic actions of those at war. But the peacekeepers? Who tells their stories?

At the beginning of the 1990s, the world exited the cold war and entered an era of great promise for peace and security. Guided by an invigorated United Nations, the international community set out to end conflicts that had flared into vicious civil wars and to unconditionally champion human rights and hold abusers responsible. The stage seemed set for greatness. Today that optimism is shattered. The failure of international engagement in conflict areas ranging from Afghanistan to Congo and Lebanon to Kosovo has turned believers into skeptics.

The Fog of Peace is a firsthand reckoning by Jean-Marie Guehenno, the man who led UN peacekeeping efforts for eight years and has been at the center of all the major crises since the beginning of the 21st century. Guehenno grapples with the distance between the international community's promise to protect and the reality that our noble aspirations may be beyond our grasp.

The author illustrates with personal, concrete examples-from the crises in Afghanistan, Iraq, Congo, Sudan, Darfur, Kosovo, Ivory Coast, Georgia, Lebanon, Haiti, and Syria-the need to accept imperfect outcomes and compromises. He argues that nothing is more damaging than excessive ambition followed by precipitous retrenchment. We can indeed save many thousands of lives, but we need to calibrate our ambitions and stay the course.