In one case in March 2007, the failure of the enemy to do just that came down to a single soldier, Sergeant Jason Stegall (tip to Instapundit), preventing a disaster :
Stegall took the M-240 machine gun, braced himself and fired a burst into the ground. The truck sped up. Stegall then opened up a sustained burst into the grill of the truck. The truck turned right off the asphalt into the dirt and Stegall unleashed a hail of bullets into the cab of the truck killing the driver. It did not turn toward the outpost, it rolled east then exploded.
Al Qaida's deadly plan had been thwarted.
Had the giant VBIED struck home, the company base would have been wide open for a second VBIED and ground assault. It could have been a massacre. Instead, we held and drove the enemy off.
Stegall was felled not by the enemy, but by illness this last December. His life ended early, but in his short time on Earth, he saved 100 others, allowing them the chance to live a full life. And he prevented a defeat during a critical period of the war when the determination of our Congress to win the war hung in the balance and the surge had yet to begin in earnest.
We are lucky to have such men in uniform.
