Expert Intuition in Battle

Gut feelings and pattern recognition save lives:

“We had indicators we’d look for, but you’d really have to be aware of everything, every detail,” said Sergeant Tierney, whose unit was working with the Iraqi police in that summer of 2004.

In recent years, the bombs have become more powerful, the hiding places ever more devious. Bombs in fake rocks. Bombs in poured concrete, built into curbs. Bombs triggered by decoy bombs.

“On one route sweep mission, there was a noticeable I.E.D. in the middle of the road, but it was a decoy,” said Lt. Donovan Campbell, who in 2004 led a Marine platoon for seven months of heavy fighting in Ramadi and wrote a vivid book, “Joker One,” about the experience. “The real bomb was encased in concrete, a hundred meters away, in the midst of rubble. One of my Marines spotted it. He said, ‘That block looks too symmetrical, too perfect.’ ”