In Louisiana, a bid for speedier infantry

"They're at 1 o'clock. Let's go!" Capt. Fred Tanner shouts to his driver, who pivots the Stryker armored vehicle and zooms off.

Tracking forces on a digital screen, the lanky officer navigates as the Stryker weaves through dark pinewoods toward an "enemy" location. Meanwhile, he taps out an e-mail alerting nearby US forces to the chase.

Although he's fighting mock skirmishes in the chigger-infested Louisiana swampland, Captain Tanner is on the front lines of a very real battle. The objective: to transform how the Army fights.

Tanner is a pioneer in the Army's first new armored force in decades - the Stryker brigade. Six of the $1.5 billion brigades are now planned, each with 3,600 soldiers equipped with about 300 medium-armored eight-wheeled Stryker vehicles.

Most immediately, the Strykers are designed to fill what the Army calls a "critical shortfall" between light infantry and heavy-armored units evident in post-cold-war missions from Somalia and Bosnia to Afghanistan and Iraq.

"We have the best heavy forces in the world, but it takes them awhile to get there," says Maj. Harris Morris of the Army's Training and Doctrine Command. Light infantry can drop into the battlefield rapidly by air, but "once they get there, if they face a heavy mechanized threat, they don't have the capability to fight that," he says.

The first Stryker unit - the 3rd Brigade of the 2nd Infantry Division based at Fort Lewis, Wash. - is scheduled to finish several grueling weeks of operational exercises here today. If the evaluation succeeds and the defense secretary certifies to Congress that the brigade is effective, it could be ready to deploy abroad by fall.

Over the next 10 years, Stryker units are also intended to spur innovation and serve as a catalyst in the Army's transition away from cold-war-era "legacy" forces to a Future Combat System that is still in the blueprint phase.

"The importance of the Stryker brigade is to transform the leadership," says Lt. Col. Len McWherter, commanding the new brigade's 1-23 battalion from a backwoods tent here. "You need creative, flexible thinkers," he says, as his staff monitors friendly and enemy forces on digital displays. "These young captains ... have to harness the technology."

Like the future force, the Stryker brigades aim to leverage instant communications and surveillance technology - from the Internet to unmanned drones to computers that track forces in real time - in order to spot the enemy first and strike at will.

Organizationally, the Stryker brigades are prepackaged for combat. They integrate reconnaissance squadrons, military intelligence companies, and other forces year-round that are now normally attached to brigades only for large training exercises or war.

With better command-and-control systems, the brigades are intended to operate dispersed over a 20 square-mile area that includes cities and hilly, vegetated terrain. As a result, they have pushed down to the company level a bigger range of weaponry, from sniper teams to 120-mm mortars and 105-mm mobile gun systems designed to destroy bunkers and blast holes in buildings during urban fighting.

A key mission of the Stryker brigades is as an "early entry" force that would fly into enemy territory on the heels of Airborne troops once they capture a landing strip. The Strykers offer soldiers greater firepower, armored protection, and ground mobility than exist in airborne or light-infantry units. Compared with heavy-armored vehicles, Strykers are quicker and more agile, with speeds of 60 m.p.h on roads and 45 m.p.h. cross country. And unlike tanks and Bradleys, Strykers are small and light enough at 19 tons to fit onto the C-130 transport planes that are the workhorses of the Air Force, allowing for deployment in days rather than weeks.

The Strykers come in 10 different variants - from infantry carriers to antitank systems - all on a common chassis. The standard design makes resupply easier and minimizes the number of spare parts for repairs. "We put more tooth in the fight than tail," Colonel McWherter says.

Soldiers testing out the Strykers offer a nuts-and-bolts view of how the new technology is performing.

At Fort Polk, the Strykers were able to converge so quickly to destroy guerrilla forces that a significant number of replacements had to be inserted into the exercise early on. Still, officers monitoring the action urged the better use of intelligence to coordinate surprise, combined-arms attacks. "We're leading with our chin," one colonel said.

The Stryker troops, who range from airborne infantrymen to tank drivers, also offer a unique perspective on the shift in Army culture required by the new brigades.

"This is the melting pot of the Army," says 2nd Lt. Jason Ford, a longtime Army Ranger from Albuquerque, N.M. "The mechanized guys have a different mentality from guys used to going everywhere with a ruck on their back or sliding down a rope," he says.

Indeed, many foot soldiers like Lieutenant Ford remain wary of relying on a vehicle - even a fast one that can stop a .50-caliber machine gun round. "If I'm stopped for 60 seconds, that's 60 seconds too long," he says. Still, Ford and others appreciate arriving fresh and rested for battle. "I don't care how well trained and physically fit you are - there are limits to your mobility," says Tanner, an Airborne officer.

Some former tank and Bradley crew members miss their old tracked vehicles. "If we were sent to war, I'd still rather be on a tank," one admits. Others, however, embrace the Stryker's antitank and mobile gun systems. "It still has a turret. It still has a gun. To me, it still looks like a tank," says Staff Sgt. David McCracken, an 18-year veteran of heavy armored units. An extra layer of armor can be added to the Stryker to protect against rocket-propelled grenades.