Col. David Perkins studied the 200-yard concrete and steel bridge at Hindiyah, unfazed by the Iraqi soldiers shooting at him from the other side of the Euphrates. No, he told his men, this bridge wasn't worth taking.

Perkins, commander of the Army's 2nd Brigade, 3rd Infantry Division, sent a few armored vehicles part way across, just to give the Iraqis the impression he wanted to seize the river crossing in this sleepy town 50 miles south of Baghdad. Then he led a contingent of his men to the town's abandoned Baath party headquarters, where they destroyed a large weapons cache.

The March 31 attack at Hindiyah was a feint, designed to draw Iraqi Republican Guard troops down river from Musayyib, the place where the division wanted to cross the Euphrates. It was the opening maneuver of what would become a stunningly swift push to Baghdad.

In just four days, four Army brigades would sprint 50 miles and four U.S. Marine brigades nearly 100 miles to the gates of Baghdad, setting the stage for this week's assaults inside the capital.

The stunning advance, at a cost of fewer than 10 U.S. combat deaths, would silence complaints by television generals, and even some officers in the field, that the war was being mismanaged. It would also provoke another kind of talk.

"The U.S. advance on Baghdad is something that military historians and academics will pore over in great detail for many years to come," British Air Marshal Brian Burridge said Monday. "They will examine the dexterity, the audacity and the sheer brilliance of how the U.S. put their plan into effect."

Already, military analysts are comparing the advance to Gen. George S. Patton's brilliant attack across northern France in the autumn of 1944.

Instead of getting bogged down in pitched battles for cities along the road to Baghdad, U.S. forces raced directly to their main objective, pausing to fight only when given the chance to exact a heavy toll on the Iraqis.

The speed of the assault and the intensity of the accompanying air campaign gave Iraqi units little opportunity to retreat and regroup; the U.S. advance quickly gobbled up the Iraqi rear.

It began as a three-pronged assault.

Part of the 1st Marine Expeditionary Unit was in the center, driving north between the Euphrates and Tigris rivers. To the east, the rest of the unit advanced toward Baghdad along the Tigris. On the west, the Army's 3rd Infantry Division drove north along the west bank of the Euphrates. In all, the advance involved fewer than 40,000 men — far smaller than the Iraqi force guarding Baghdad.

Every night, F/A-18 Hornet and F-14 Tomcat strike fighters screamed off aircraft carriers, hunting down Iraqi tanks, artillery and command centers to lay the groundwork for the next day's advance. B-52s and Tomahawk missiles added to the destruction.

Captured Iraqi soldiers described searching in vain for shelter during bombardments that turned Iraqi vehicles into pillars of smoke. Deprived of their equipment, Republican Guard troops began abandoning positions and shedding their uniforms.

Continual bombing of Iraqi communications and command centers in Baghdad apparently made it impossible for senior officers to mount an organized defense.

Here and there, advancing U.S. forces met spirited but often poorly organized resistance.

At dawn on Tuesday, April 1, the 4th Marine Regiment — the middle prong of the advance — moved on Diwaniyah, 80 miles south of Baghdad, and encountered Iraqis armed with rocket-propelled grenades, Kalashnikovs and machine guns.

"The Iraqis were pretty determined," said Lt. Col. B.P. McCoy. The fighting lasted until mid-afternoon. At least 75 Iraqi troops were killed and 44 taken prisoner.

The Marines had no interest in occupying the town. They simply destroyed the Iraqi force and kept moving.

To the west, the 3rd Infantry Division was approaching the Karbala Gap, a narrow strip of land between the Euphrates and a reservoir west of the city of Karbala. It was a natural place for Iraqi forces to try to stop the advance.

The expected heavy resistance never materialized.

"It was amazing," said Lt. Col. Scott Rutter.

On Wednesday, April 2, his battalion held off a small force of Iraqi troops while the rest of the 1st Brigade poured through the gap. By midmorning, it reached the Euphrates at Musayyib, just 40 miles southwest of Baghdad.

There, the 1st Brigade found the bridge rigged with explosives but only lightly defended.

"First we destroyed all the near-side forces," Lt. Col. Ernest "Rock" Marcone told Washington Post columnist Michael Kelly. "Then with artillery and aviation we destroyed much of the far side."

Working from boats, Army engineers defused the explosives, and two tank companies and one infantry company rolled across to put down what little resistance remained.

"By full dusk, the sporadic mortar fire had ceased," Kelly wrote. "Everything was quiet except for an occasional bit of light arms fire in the farm fields beyond the bridgehead."

No American solders were killed in the encounter, but the following night Kelly and his driver drowned when their Humvee swerved to avoid enemy fire and rolled into an irrigation ditch.

On the Tigris River, Marines in the eastern prong of the advance were taking a bridge of their own that Wednesday.

According to intelligence reports, the river town of Numaniyah was defended by one company of Iraqi troops, and the adjacent bridge by another.

But as they drove toward town on Highway 6, the Marines saw signs that resistance had crumbled in the face of aerial bombardment. Corpses lay under blankets by the side of the road. The ground was littered with discarded Iraqi uniforms, rifles and mortar ammunition.

There were also a few abandoned gas masks, still sealed in their plastic bags — a reminder that a chemical attack might come at any time.

At the edge of town, Marines spotted a man trying to pull a brown robe over his uniform. They took him prisoner, penning him up with dozens of other men in similar attire.

The Marines approached the Numaniyah military barracks with care, trotting hunched over to the buildings while their comrades covered them.

The barracks were empty, their inhabitants gone who-knows-where.

By Thursday, April 3, the Marines in the center prong suddenly veered northeast toward Kut, a small city on the Tigris. There, they joined the eastern prong of the advance in a powerful thrust toward Baghdad.

At Kut, friendly townspeople and farmers lined the roads as the American tanks and Bradley fighting vehicles rolled by.

"God help us, because Saddam Hussein is killing us," said Kasem Fasil, an elderly man with a single jagged tooth.

But it was here that Baath party fighters and Republican Guard soldiers made a stand, hiding in a grove of date palms and nearby buildings.

As fire from the Marines thinned their numbers, a few Iraqis tried a desperate assault.

"They came charging in a human wave, 10 or 15 guys," said McCoy, the commander of the 4th Marine Regiment's 3rd Battalion. "We mowed them down."

Two Marines were killed in the engagement.

Searching Kut for weapons, the Marines found an impressive arsenal, including mortar rounds, grenades, small arms ammunition and a trove of chemical protection suits.

On Thursday, McCoy's battalion crossed into the "red zone," a perimeter around Baghdad where intelligence suggested Saddam might use chemical weapons. Although temperatures topped 90 degrees, they pulled on their sweaty chemical protection suits.

By that evening, the Army's 3rd Infantry Division had reached the outskirts of Baghdad. Coalition aircraft had been dropping bombs in the area all day, hitting artillery, military buildings, dug-in vehicles, a presidential palace and the Baghdad airport.

The Army's 2nd and 3rd Brigades went on raids Thursday and Friday, expanding U.S. control around southern Baghdad. The 1st Brigade attacked the international airport.

The fighting there grew chaotic as Iraqi forces launched a counterattack, but by dusk the action subsided. Dead Iraqi soldiers lay scattered, their waxy faces staring blankly.

Soldiers moved from terminal to terminal, methodically securing the airport even as Iraq's information minister insisted that troops loyal to Saddam still held it.

The Marines, too, moved to within sight of Baghdad's skyline, poised to join the final fight. From their camp on Friday night, the leathernecks watched a veritable fireworks show as U.S. planes hit targets inside the city with tons of munitions.

Saturday morning was another hot one. Despite concern about chemical attack, many Marines stripped off their protective suits and rigged up makeshift showers.

The respite was brief. Within hours, they would be firing across a reedy marsh at foreign partisans who came to Baghdad to fight for Saddam.

By Saturday morning, U.S. forces had surrounded Baghdad and the ground attack on the city began.

In the days since, U.S. troops have moved from engaging in running battles and pinpoint strikes on the city's outskirts to attacking the very center of Baghdad.