DAHANEH, AFGHANISTAN » Kaneohe Marines battled Taliban fighters yesterday for control of a strategic southern town in a new operation to cut militant supply lines and allow Afghan residents to vote in next week's presidential election.

Insurgents appeared to dig in for a fight, firing volleys of rocket-propelled grenades, mortar rounds and even missiles from the back of a truck. By sunset, the Marines had made little progress into Dahaneh beyond the gains of the initial pre-dawn assault.

Fighting accelerated after sundown, and officers predicted a couple of days of intense combat before the town could be secured.

“;Based on the violence with which they've been fighting back against us, I think it indicates the Taliban are trying to make a stand here,”; said Capt. Zachary Martin, commander of Golf Company, 2nd Battalion, 3rd Marine Regiment, based at Kaneohe.

The operation, Eastern Resolve 2, was launched late Tuesday Hawaii time with 400 Marines and 100 Afghan troops, who leapfrogged over Taliban lines in helicopters to attack militant positions in mud-brick compounds at the edge of town.

It was the third major push by U.S. and British forces this summer into Taliban-controlled areas of Helmand province, the center of Afghanistan's lucrative opium business and scene of some of the heaviest fighting of the Afghan war.

British troops have been responsible for Helmand the last three years, but never had enough forces to take and hold Dahaneh, a squalid town of about 2,000 people. Marines say the town is key to controlling the Naw Zad valley, a major Taliban staging area and large opium market site.

The Marines are part of the 21,000 additional forces President Barack Obama deployed to Afghanistan this year to stop the Taliban's violent momentum.

U.S. and British troops hope to break the Taliban grip on the province, sever smuggling routes from Pakistan and protect the civilian population from Taliban reprisals so Afghans can vote next Thursday. The Taliban have called for a boycott of the ballot and threatened to ruin the election.

A first wave in Humvees and MRAPs left a Marine base at 1 a.m. in the town of Naw Zad, about five miles north of Dahaneh. Three CH-53 Sea Stallion helicopters then picked up a platoon and dropped the Marines behind Taliban lines. These troops blasted their way into a suspected militant compound, where they arrested five men and took the compound as a base.

Just before morning light, militants unleashed their weapons. “;Incoming!”; the Marines cried out as the whistles of rockets approached. A heavy rocket targeted a Marine outpost but flew over the small base, while a mortar round landed just 20 yards from a Humvee on the town's outskirts.

“;Just a few meters farther and I'd be dead,”; said Cpl. Joshua Jackson, 23, of Copley, Ohio, after one round landed nearby.

Short bursts of fire punctuated the desert air through the next eight hours, a response so fierce troops suspected militants knew they were coming.

At the Pentagon, spokesman Bryan Whitman said the operation was “;going as planned.”; He would not say how long it will last.

Taliban machine gun fire slowed the Marines' progress. Militants also brought in a truck to fire heavy missiles. Marines said the Taliban's reputation for poor aim and for fleeing had not proved true.

“;This is a Taliban home down here, so for once they're not running,”; said Lance Cpl. Garett Davidson, 24, of West Des Moines, Iowa.

Complicating the fight, insurgents were shooting from house rooftops and courtyards, putting civilians in danger. But civilians—perhaps 100—were seen running away, leaving the Marines confident that those left in the town were mostly militants.

The Marines appeared to take great care to help villagers. About a dozen Marines and Afghan troops dashed 50 yards out of their compound to help people caught in the crossfire. The Marines launched smoke grenades to obscure the rescue of five Afghan children and five adults. The villagers were then hurried into the Marine outpost.

After militants fired volleys of rockets, the Marines called in a missile strike, and Martin said seven to 10 militants were killed. “;We were tracking these individuals, they were there ... and then boom, and they weren't there,”; Martin said.

After the noon sun sent temperatures close to 120 degrees, fighting subsided. It picked up again around 4 p.m., when a Marine unit was ambushed.

Insurgents appeared to try to encircle the Marine position. Sniper and RPG fire landed near the compound, but there were no U.S. or Afghan casualties. Cobra attack helicopters circled overhead, adjusting their targets in the mountains where Taliban forces were hiding.

Militants typically avoid large confrontations with U.S. troops. Martin said the Taliban may have been tipped off, a suspicion shared by many of his troops.

“;I'd say we've gained a foothold for now, and it's a substantial one that we're not going to let go of,”; he said as RPG fire landed nearby.