Civilian leaders, meanwhile, in Paris as much as in Washington, boxed themselves in with their constant public affirmations of the conflict’s importance and of the certainty of ultimate success. To order a halt and reverse course would be to call into question their own and their country’s judgment and to threaten their careers, their reputations. Far better in the short term—always the term that matters most to the ambitious politician—to forge ahead and hope for the best, to ignore the warning signs and the contrary intelligence and diplomatic reports.

