Ideally, the average soldier carries no more than 48 pounds of gear into battle, and 72 pounds when marching. War rarely meets ideal conditions. Paratroopers fighting in Iraq in April 2003 carried up to 101 pounds, which rapidly led to exhaustion and proved taxing even for physically fit soldiers. Body armor accounts for between 20 percent and 30 percent of the weight, and obviously must be worn by the soldier. But spare batteries, extra socks, hygiene kits, and ponchos don't always need to be carried by humans. BigDog would follow closely behind a leader and obey voice commands. It could also serve as a mobile power station, recharging batteries for troops on the move.