Frederic Hof, a former U.S. diplomat now with the Atlantic Council, sums up the bloody impasse on the Turkish-Syrian border as “a fine kettle of fish,” quoting a phrase used by comedians Stan Laurel and Oliver Hardy. He means that it’s a “confused, awkward, messy and even intractable situation,” with Americans and Turks, supposedly allies, castigating each other for taking insufficient action.

“Don’t fight the problem. Decide it!” argued Gen. George C. Marshall, one of America’s wisest military leaders. In the Iraq-Syria case, this logic would identify the inescapable parameters of the conflict. Turkey is a difficult ally but an essential one; doing nothing against the Islamic State would be unacceptably risky, but total war isn’t a realistic option; the U.S. campaign may have begun awkwardly, but that’s no reason to panic.

Military history is usually a story of persistence and will, as commanders muddle through the bad opening months of battle. Marshall’s experience in World War II was a classic example: The North African and Italian campaigns were one disaster after another, as Rick Atkinson explains in his brilliant trilogy about the war in Europe. The United States kept stumbling forward to the D-Day landings and pushed on to eventual victory.