Many people may not realize when and where Global Positioning System (GPS) technology came to fruition. The NAVSTAR Global Positioning System was first introduced by the US Air Force in the mid1960s, eventually becoming a Department of Defense (DOD) project. The system was designed to determine positional information on Earth through the use of a constellation of orbiting satellites. The first GPS satellite was placed in orbit In 1978. Once complete, the system was to have 24 satellites, providing unlimited two and three-dimensional coverage 24 hours a day. When the U.S. Army deployed for Operation Desert Shield in 1990, 16 NAVSTAR satellites were in orbit, providing a guaranteed three-dimensional coverage lasting about 19 hours. The new devices had a built-in error of only sixty feet compared to earlier land based systems with up to eight miles in expected error.By 1991, GPS had been utilized for more than ten years by aircraft, Special Operations teams, and in limited training missions. The system was relatively unknown to much of the Army at the time. During Operation Desert Shield, Special Operations teams were inserted behind Iraqi lines with missions that would have been unthinkable without the use of GPS. With a large scale operation against the occupying Iraqi Army on the horizon, Army commanders realized the need to supply frontline units with the GPS devices. The problem was the limited number of devices on hand. In an October 1991 newsletter, the Center for Army Lessons Learned (CALL) noted only 500 demonstration receivers were owned by the Army at the outset of Operation Desert Shield. As a result, commercial receivers were rapidly procured. Still, when operations started on February 24, 1991, only selective units and vehicles were equipped with the new technology. For example, of the VII Corps' 40,000 vehicles in theater, only 3,000 received a GPS unit. Those vehicles needing the devices often included forward and reconnaissance elements, unit commanders, and artillery surveyors. There were instances of troops buying their own GPS devices. Lieutenant General Frederick Franks, the VII Coprs Commander, noted after the war, "They [GPS receivers] were invaluable in avoiding fratricide and allowing accurate navigation and artillery fires."G-day came on February 24, beginning at 0400. U.S. Army units in both the VII Corps and XVIII Airborne Corps quickly realized the value of the GPS units. With the unexpectedly rapid advance of coalition forces, heavy reliance was placed on these small devices while navigating in a featureless desert landscape. The 24th Infantry Division used the receivers to link phase lines for the assault, helping to maintain command and control. Although seven different types of GPS devices were used during the war two models comprised the clear majority. The AN/PSN-10 Small Lightweight GPS Receiver (SLGR, pronounced "Slugger") was favored with approximately 4,000 devices deployed. The SLGR is a small rectangular, box-like hand-held unit developed by Trimble Navigation. It weighs about four pounds and can be mounted to a vehicle or aircraft. The second most prevalent device was the NAV 1000M Receiver, made by Magellan, still a leading company in GPS technology. It was smaller than the SLGR and is powered by AA sized batteries. Approximately 1,000 of these devices were utilized during the war.The relatively new Global Positioning System receivers aided the U.S. and coalition forces in winning Operation Desert Storm after only four days of ground combat. It was the first major land campaign involving the widespread use of GPS. The space-based navigation technology joined the U.S. military's arsenal of combat capabilities. By 1995, all 24 NAVSTAR satellites were in orbit, providing world-wide coverage 24 hours per day. Today, GPS technology is prominent in both military and civilian applications. From weapons systems and precision guided ordnance to individual receivers for our warfighters abroad, GPS capabilities are now essential. The system has advanced our nation's navigational abilities and warfighting capabilities to a very high standard.