 He applied metrics (body counts) to determine how close to success his plan was.Faced with a guerrilla war, the question of holding territory was irrelevant as the VC never operated for extended periods in areas where the Americans were strong and if the Americans occupied an area in force, the VC simply moved to other areas where the American presence was weaker.McNamara devised the "body count" measurement to determine how well the Americans were doing, reasoning if the Americans were inflicting heavy losses as measured by the "body count", it must be a sign that they were winning.