Fort Polk, La. ? Instead of kicking its tires, Gen. Eric Shinseki evaluated the Army’s new armored vehicle by interrogating the soldiers who had driven it, repaired it and maneuvered it through miles of pine forest in west-central Louisiana.

His verdict: “It’s ready.”

The Army and the rest of the U.S. military are changing profoundly, and the eight-wheeled Stryker — surprisingly quiet as it streaks down a dirt path at 60 mph — is leading the way.

Shinseki, the Army chief of staff, spent a recent day at Fort Polk to get a firsthand look at the Stryker and the new combat organization built around it, the Stryker Brigade Combat Team. Both are to be declared ready by late summer for combat missions anywhere.

It was Shinseki’s final visit with soldiers in the field before retiring as Army chief on Wednesday. He is ending a 38-year career that included service in Vietnam, where he lost part of a foot, and as commander of U.S. peacekeeping forces in Bosnia. The White House has not nominated his successor.

The Stryker symbolizes a historic step toward the goal Shinseki announced in October 1999. He wanted to remake the Army by 2010 into a more versatile force that can move quickly onto distant battlefields, armed with unparalleled ability to dictate the pace of fighting.

“The Stryker is going to be one of the enduring legacies of Shinseki’s leadership,” said Dan Goure, a defense analyst with the Lexington Institute in Arlington, Va. “This is the leading edge.”

Eventually there are to be six Stryker brigades with about 3,500 soldiers each, capable of arriving at a hot spot within days. That is far quicker than a traditional armored unit built around the unmatched firepower of the tank, which weighs three times more than a Stryker.

Barely three years ago, the Stryker was little more than an idea on paper, and not a terribly popular one.

Armor loyalists scoffed at the notion of wheeled maneuver forces. But Shinseki insisted it could and must be done to give the Army the mobility and agility needed to maintain relevance in the 21st century.

Fred Beebe, hidden in the front hatch driving, and Floyd Newell, top, from General Motors/General Dynamics, demonstrate the new Stryker combat vehicle at Fort Benning, Ga. A Stryker Brigade Combat Team will be formally declared ready for combat missions anywhere in the world by late summer.

Shinseki visited the Stryker brigade as it neared completion of 10 days of nonstop exercises at Fort Polk’s Joint Readiness Training Center.

Inside a set of tents that formed the brigade’s tactical operations center, Shinseki sat on a plastic chair facing the commanders of two infantry battalions, an artillery battalion and a cavalry battalion. He outlined the rationale for creating Stryker brigades:

l The Stryker has superior speed, which allows battlefield commanders to quickly seize what Shinseki called the “Big I” — the initiative. “Once you’ve got it, hold onto it,” he said.

l The brigade is organized to enable its command network to keep up with the fighting and support forces. In other words, its vital communications links — for intelligence, surveillance and command — can be maintained 24 hours a day across a larger geographic area.

l The focal point of a brigade is its infantry, which can advance more quickly and with less effort than the soldiers who are carried in today’s Bradley Fighting Vehicle or armored personnel carrier. Shinseki cited examples from the Iraq war of how dismounted infantry can be more effective than tanks against paramilitaries holed up in a mosque or school.