A U.S. Army force spearheaded by tanks and armored fighting vehicles pushed ever deeper into Iraq today, meeting only light resistance from Iraqi soldiers and receiving a mostly wary response from civilians as it raced northward with a mission to destroy President Saddam Hussein's government and armed forces.

Driving toward Baghdad from the Kuwaiti border, columns of the 3rd Infantry Division passed through sparsely populated areas mostly unmolested. But in a town south of the Euphrates River, soldiers of the division's 2nd Brigade engaged in a gun battle with Iraqi troops, killing 45 of them with the help of artillery fire, according to Lt. Col. Stephen Twitty, commander of the 3rd Battalion, 15th Infantry Regiment. There were no casualties on the U.S. side.

In another incident, a lone mortar round landed about 400 yards from a major refueling point for 2nd Brigade armor, causing no damage or casualties. Twitty said the location of the incidents could not be identified under ground rules designed to protect U.S. troops as they sweep northward across the Iraqi desert to the southwest of the Euphrates. But Pentagon officials said the 3rd Infantry Division's lead elements had pierced 150 miles inside the country -- about halfway to Baghdad. "The [soldiers] had a pretty good fight up here," Twitty said, referring to the 2nd Brigade's clash, during a brief interview at a refueling point before continuing his road march. "They killed 45 guys."

When his command sergeant major, Robert Gallagher, approached him on the rocky flat that served as the refueling point, the two men, who had taken different routes, hugged and patted each other on the back.

"Thanks for getting this stuff here, man," Twitty told Gallagher. He said his column had been driving at nearly top speed through the night. "We were jumping dunes," Twitty said. All the vehicles made it except for one M1 Abrams tank and an M2 Bradley Fighting Vehicle, he said, "amazing."

Until reaching the vicinity of the refueling point, Twitty said, the column met "zero resistance."

A similar scene played out when Bravo Company's commander, Capt. Ronnie Johnson, met his first sergeant, Chris French, at the refueling point. As they embraced, a soldier watching called out, "Can I get a hug, too?"

With visibility reduced to a few yards at times in the choking dust, Johnson said the vehicles in his convoy kept bumping into each other.

"We had seven crashes, but we didn't get anybody killed, so it was a good night," he said.

Thousands of troops and vehicles of the 3rd Infantry Division, including tanks and Bradleys, poured across the Kuwaiti border two days ago. Commanders said the U.S. force was headed for a potentially decisive battle in the Bush administration's campaign to oust Hussein.

"Long, treacherous and dirty," was how one Bradley driver, Spec. Eric W. Huth, of Cincinnati, described the road march. He said the group passed one shepherd who was smiling and blowing kisses.

For the most part, however, civilians who watched the U.S. convoys pass them on the roads reacted cautiously. A number of people, especially children, smiled and waved, but most of the men looked on without expression, showing neither joy nor anger at the U.S. invasion force.

A truck driver stranded by the road scratched his head as he inspected the front of his vehicle, studiously ignoring the tons of steel rumbling past him. Many others also kept their distance.

One smiling man, wearing a traditional long robe and squatting by the side of the road, spread out his hands with his palms up as if to say, "What's all this?"

As the convoy entered a more populated area, the response became somewhat more animated. Children lined the road, smiling and waving. But the U.S. soldiers remained on alert. One scout radioed to the column to watch out for someone in a window of a building who appeared to be "holding something." Similar alerts went out concerning people standing on rooftops.

As the column advanced, the arid landscape gave way to green fields and the smell of manure. A light drizzle kept the dust down, and cool temperatures made the soldiers' protective suits -- designed to safeguard them from chemical or biological attack -- somewhat more bearable to wear.

Soldiers from the 3rd Battalion, 7th Infantry Regiment watch a convoy of 3rd Infantry Division artillery pass by.