“Can someone tell me why the Marines were sent to Helmand?” the incredulous McChrystal asked his officers.

The answer — not fully known at the time to McChrystal and his officers — would reveal the dysfunction of the U.S. war effort: a reliance on understaffed NATO partners for crucial intelligence, a misjudgment of Helmand’s importance to Afghanistan’s security, and tribal politics within the Pentagon that led the Marines to insist on confining themselves to a far less important patch of desert.

The consequences were profound: By devoting so many troops to Helmand instead of Kandahar, the U.S. military squandered more than a year of the war. Had the initial contingent of Marines been sent to Kandahar, it could have obviated the need for a full 30,000-troop surge later that year, or it could have granted commanders the flexibility to combat insurgent havens in eastern Afghanistan much sooner, allowing them to meet Obama’s eventual withdrawal deadlines without objection.