The Marines of the Two-Seven were not even supposed to deploy to Afghanistan. Their original destination was Iraq, and when they were sent here in April as a stopgap measure to help an overwhelmed NATO force, the plan had been to spend the time mentoring Afghan national police.

It didn't turn out that way.

Instead of training policemen, the lightly equipped 2nd Battalion, 7th Regiment of the 1st Marine Division found itself engaged in firefights with insurgent units of 100 or more fighters. They faced Taliban snipers and roadside bombs.

Twenty members of the battalion died in combat.

"It definitely was a lot worse than we expected," said Cpl. James Flores, 22, of Thousand Oaks, Calif. "A lot more active."

The 1,000-member Two-Seven has begun returning to its California desert base in Twentynine Palms northeast of Los Angeles; the bulk will be home by early December. The members take credit for leaving behind 800 trained Afghan police, hundreds of dead Taliban fighters and nascent diplomacy with village leaders.

They also served notice that the Marines were back in Afghanistan to stay.

HAWAI'I UNIT CALLED UP

Based in part on the experiences of the Two-Seven and the grit of its individual members, Marine Corps officials are planning to expand their numbers greatly here — an unexpected result of a deployment that wasn't even supposed to be.

A replacement task force will consist of about 2,300 troops, more than double the size of the Two-Seven's initial deployment. It will include infantry from Camp Lejeune in North Carolina, an air wing from Miramar Marine Corps Air Station in San Diego and a headquarters unit from Hawai'i — a "special air-ground" task force with all the gear, air power and other assets the Two-Seven lacked when it arrived. An unspecified number of Marine special operators are also in Afghanistan.

Among the Hawai'i Marines from Kane'ohe Bay are about 120 Marines from the 3rd Marine Regiment and 230 Marines with Combat Logistics Battalion 3.

Lt. Gen. Samuel Helland, commander of the Marine Force Central Command, said he would like 15,000 Marines sent here soon "to crush the enemies of Afghanistan."

LAST-MINUTE MOVE

That was never part of the plan. When Commandant Gen. James T. Conway first suggested that Marines be shifted from Iraq to Afghanistan, U.S. Defense Secretary Robert M. Gates rejected the idea.

Months later, under pressure to bolster NATO allies in Afghanistan's troubled south, Gates relented. He agreed to send the Two-Seven to Helmand province and deploy the much larger 24th Marine Expeditionary Unit from Camp Lejeune several hundred miles to the east.

The seven-month deployment, Gates said, was "one time" only.

The last-minute move meant the Marines were not accompanied by their usual combat weaponry and gear: heavy artillery, tanks, aircraft, a full-scale supply system and a full reconnaissance unit.

Like the Army, the Marine Corps was stretched thin on equipment and manpower. The Two-Seven's basic mission — mentoring the Afghan national police in sprawling Helmand — was not expected to involve continuous combat.

But the Marines were attacked repeatedly as they established forward bases in the region and began to make contact with local villagers. Before long, the fighting overshadowed the mentoring. Although they had expected to be tested by the Taliban in an area where much of the poppy crop that funds the insurgents is grown, they had not anticipated the intensity of the conflict.

INTENSE FIGHTING

For six months, the Two-Seven had more members killed and wounded — about 150 — than did the 20,000 Marines deployed in Iraq. It also did its share of killing.

A Marine sniper killed 12 insurgents in one battle alone and since arriving in Afghanistan has killed 28, Marine officials said.

"Our guys were running and gunning so fast that the up-tempo was crushing," said Lt. Col. Rick Hall, the battalion commander.

Because of the ferocity of the fighting, Marine officials began providing helicopters and other supplies needed by the Two-Seven. The choppers were transferred from Iraq.

Meanwhile, the efforts to recruit and train Afghan police officers were beset by corruption and narcotics. In one class of 100 recruits, 35 were dismissed because of drug use.

The battalion also faced a manpower shortage in mid-deployment as 150 members neared the end of their active-duty stints. An urgent call went out corps-wide for volunteers, and more than 300 Marines stateside stepped forward. About 140 were accepted.

"Not a day goes by when I don't mention the warriors of Two-Seven and the great things they're doing," Sgt. Major Randall Carter, top enlisted man at the 1st Marine Division, told Marines at Delaram. "You've been out here alone and unafraid."

'A LONG WAY TO GO'

Over the summer, Gates ordered the latest deployment lengthened by a month.

Maj. Gen. Thomas Waldhauser, commander of the 1st Marine Division, said Marines, in effect, were starting over in Afghanistan after being the lead U.S. conventional force in toppling the Taliban regime in 2001.

"This is where it all started," Waldhauser told the troops at Delaram. "We're just starting over again. We're going to be at this a long time."

After routing the Taliban, the Marines mostly were redeployed to Iraq. A special operations unit arrived in early 2007 but was sent home amid controversy over civilian deaths.

Although commander Hall is proud of his battalion's accomplishments, he says the victories have been incremental. "We haven't won anything yet. We've got a long way to go," he said.

The deaths of 17 Marines, one soldier, one Navy corpsman and an interpreter continue to wear on Hall.

The 49-year-old father of 10 is in e-mail contact with many of the families of the fallen, and his eyes take on a faraway look when he mentions them.

"The character of these families is incredible," he said.

"They talk about Afghanistan being the forgotten war," Hall said at his office at the Bastion base, shared by the U.S. and Britain. "It certainly was on our watch."