FOR almost three-quarters of a century, highly trained groups of Soldiers have been inserted behind enemy lines to disrupt the movement of enemy troops and supplies to the front lines. These brave Soldiers have frequently used parachutes as a means to infiltrate without being detected.Although most of the airborne forces of the world still use round parachutes, some specialized military free-fall units use ram-air airfoils, which provide control of speed and direction, as their primary means of infiltration.Descending from the skies at 12,500 feet, traveling nearly 120 miles per hour, free-fall parachuting is the closest humans have ever come to actually flying. For the Black Daggers, the official U.S. Army Special Operations Command Parachute Demonstration Team, that's a typical Monday morning.During their two-mile drop, the Black Daggers maneuver their body using their hands, arms, legs and shoulders to control their flight. At a few thousand feet, they deploy their parachutes and land with pin-point precision, whether it's in a football stadium or on their training grounds near Fort Bragg, N.C.Their mission is to perform live aerial demonstrations in support of Army special operations community relations and recruiting. Composed of volunteers from throughout Army special operations, the Black Daggers have diverse backgrounds and are skilled in various military specialties including Special Forces, Rangers, civil affairs, psychological operations, and signal and support. With an average age of 33 and an average number of free-fall jumps at 560, the team represents the professionalism and dedication of Army special operations forces.Although they are capable of performing both high-altitude, low-opening and high-altitude, high-opening jumps, the principle technique demonstrated by the Black Daggers is the HALO. This form of stealth insertion used to land troops and equipment behind enemy lines was first conducted in combat during the Vietnam War by the Military Assistance Command, Vietnam-Studies and Observations Group, a multiservice U.S. special operations unit in which Army Special Forces played a large role.After exiting an aircraft at high altitudes, sometimes upwards of 25,000 feet, where oxygen is scarce, the jumpers fall to the earth, reaching terminal velocity before deploying their parachutes and gliding in under enemy radar.The Black Daggers use the military variant of the ram-air parachute. These flexible-wing gliders allow a free-fall parachutist the ability to jump with more than 100 pounds of additional equipment attached to him. In addition to the extra weight, the jumper must also withstand high winds, frigid temperatures and low oxygen levels, all of which require the jumper to be highly skilled.