PHOTO: David Leeson/ Corbis Sygma

On 1 April, a brigade of U.S. Army tanks moved in for a nighttime assault east of Karbala, near Iraq's Euphrates River. The lead company's commander, Captain Stuart James, planned to pass between two other U.S. units, beyond which lay enemy territory. Once clear of the other units, James would give the order “Red free,” which meant, essentially, “Fire at will.” What he didn't know, though, was that a U.S. scout platoon was on the opposite bank, on a path that would take it directly in front of James's tanks. Shrouded by a moonless sky, the scouts moved unseen. It was a disaster in the making.

But on a computer screen mounted in his Abrams tank, James had been watching a map of the vicinity. He spotted a blue icon moving in from the right: the scout platoon. Instead of “Red free,” he keyed his microphone and barked a single word: “Hold!”

Both James's and the scout platoon's vehicles had recently been equipped with a new satellite-based tracking unit that got its first real test in Iraq. Every five minutes or so, an antenna mounted on each vehicle was automatically sending out its Global Positioning System (GPS) coordinates; that signal bounced to a satellite and back down to a ground station in Kuwait [see diagram]. There, a server received updates from all the vehicles—as well as enemy locations from other sources—and sent back an aggregate set of positions to each tracking unit. James's computer screen refreshed to show the new locations—blue icons for friendly forces and red for the enemy—against a digital map or satellite image.

“I was able to look on my screen and see where my friendly units were to my left, to my right, to my front, to my rear, and I was able to pass that information immediately down to my platoon,” James later said. “Fratricide was basically eliminated.”

The big picture

In an age of sophisticated battlefield video games, where a single player can control dozens of tanks, aircraft, and other vehicles at a time, one might be forgiven for assuming that real-life soldiers have the same capability. They don't. At times, they don't even know their own locations, shuffling through dozens of paper maps and peering at GPS devices. Even commanders have at best a general idea of where their various units are at any given time. In war rooms, troop positions are designated by pins stuck into maps, the accuracy dependent on how often units radio in their positions and how well they read their maps.

That all changed in Iraq. For the first time ever, any soldier, from a private driving a truck to the commanding general at the U.S. Army's headquarters in Kuwait, could watch on-screen as tanks, helicopters, and other vehicles moved across the battlefield. With this new blue-force tracking technology—known, somewhat cumbersomely, as Force XXI Battle Command Brigade and Below, or FBCB2—they now had what military strategists have long considered the battlefield's Holy Grail: a common operational picture. That picture let everyone know what was happening as it happened.

For soldiers in the field, FBCB2 allowed them to navigate even in blinding sandstorms, to coordinate attacks with unprecedented precision, and to exchange text messages on the fly. That last feature proved essential during the Army's now-famous race across the desert to Baghdad. Many units were moving so fast, they fell out of radio range; nor could they rely on the Army's usual satellite-based communications networks, which take several days to set up and tune.

Unfortunately, only about one in 10 Army vehicles deployed in Iraq had the benefit of an FBCB2 onboard. The 4th Infantry Division, based at Fort Hood, Texas, was the only one to have an FBCB2 installed on every vehicle. In fact, because of the 4th's role in beta testing the FBCB2, the press dubbed it “the most technologically advanced fighting force in the world.” Other divisions were given 100 to 200 FBCB2s, to place on key vehicles.

The FBCB2 would have averted the much-reported incident in which Private Jessica Lynch was captured. Without adequate navigation, her maintenance vehicle took a wrong turn and collided with another Humvee, killing some of the convoy's crew.

The FBCB2 also prevents friendly fire. While U.S. combat deaths have fallen dramatically with the rise of long-range, precision-guided weapons, that greater precision hasn't eliminated fratricide, the military's term for the accidental killing or injuring of one's comrades. What's more, the proportion of fratricide deaths has remained static and may even be on the rise.

During World War II, friendly fire accounted for anywhere from 2 to 21 percent of U.S. casualties, depending on whose figures you use. During the first Gulf War, by contrast, 24 percent of U.S. casualties came from fratricide. While casualties from the Iraqi War are still being tallied, it's already known that friendly fire accounted for some 35 U.S. and allied deaths during the first six weeks of conflict, out of a total of 189 fatalities [see photo].