"It's the rule--always watch your fives and twenty-fives. When a convoy halts to investigate a possible roadside bomb, stay in the vehicle and scan five meters in every direction. A bomb inside five meters cuts through the armor, killing everyone in the truck. Once clear, get out and sweep twenty-five meters. A bomb inside twenty-five meters kills the dismounted scouts investigating the road ahead. Fives and twenty-fives mark the measure of a marine's...