By Alastair Leithead
BBC News, with British troops in Afghanistan
British soldiers have to be constantly on their guard
British forces in Helmand province are continuing to come under attack by Taleban fighters using guerrilla tactics. So how are they bearing up?
The three Chinook transport helicopters skimmed low over the sand dunes, spewing out flares to counter incoming fire as they dropped out of the setting sun into the landing zone.
Clouds of dust whipped up by the rotor blades confused the senses as the Royal Marines began the 100 metre dash down the lowering ramp, over uneven ground into the relative safety of the compound.
Echoing along the river valley was the crump of outgoing mortar fire, followed by the distant thud as the rounds landed in the known Taleban positions the British troops were targeting.
Artillery shells fizzed overhead - fired from kilometres away, and Apache attack helicopters circled menacingly - all to protect the three helicopters and their fresh deployment of Marines brought in to relieve the men of the 3 Para Battlegroup.
Sangin is one of the toughest outposts on the front line in Helmand province.
For months a small force of British troops has been protecting the local government district centre from wave after wave of Taleban attack.
This was the start of an operation to bring the men who had defended it home.
Chinook helicopters often come under fire from the Taleban
One soldier called it "the Alamo" as they have taken fire from every direction, have had to defend hard just to survive, and at times supplies have been slow in coming, forcing them to live off emergency rations and purified river water.
The quiet of the clear night sky was first broken by the eerie calls to prayer, melting together into one as they drifted up the shallow valley.
Another day of Ramadan and a sound that has started every day for centuries, but crouching behind the sandbags and firing positions in the British base, it was a stark reminder of how the war on terror is becoming a clash between Islam and the West.
A deep bass rumbled in the distance as the Chinooks swept over the desert from the main British base at Camp Bastion and came into land further up the wadi.
They dipped down and within minutes the men were out on the ground, the helicopters gone and the sun allowed to rise quietly over the ruins of Sangin market - battered by the weeks of fighting and bombing.
Slowly but surely the Paras moved through the woods and compounds, securing the area for the main airlift out later in the day.
After a few hours of gradual progress they met resistance - first came the crack of small arms fire from the woods, then the heavy machine gun from the Apache helicopter, the mortars started up once again and the fighting intensified.
Military manoeuvres have to be carefully planned
There was the whine of an American A10 bomber diving and a laser-guided bomb struck just ahead of the troops on the ground.
Then the incoming fire came from another direction.
Three rocket propelled grenades struck the front of the building, just below our vantage point on the roof - there was incoming small arms fire - for half an hour the fighting was on three sides.
Then came a lull - enough to send the helicopters in, and the now bearded soldiers of 3 Para Battlegroup made final preparations to leave.
Some had spent more than five weeks here sleeping on the floor in the dust and the insects, living off ration packs and fighting for hours every day in "the most intense fighting since the Korean War" to quote the NATO commander.
"Well, it's the worst place I've been to," said Corporal Trevor Coult of the Royal Irish Regiment - he has been awarded a Military Cross in Iraq.
"It's worse than Baghdad. It makes Baghdad look like a walk in the park compared to here."
Private Denaiewicz from 3 Para described what it had been like.
"Constant attack day and night from rocket propelled grenades, small arms fire. I think we are making a difference," he said, "but it will be a long time before we make a major impact on everything."
Two soldiers were injured in the mission - one seriously - his next of kin have been informed. They were taken away for treatment on the first helicopter to fly in.
The precautionary mortars and artillery started up again and the soldiers packed into the back of the Chinooks - their tour of duty in Sangin over.
The Marines will now bear the brunt of the fighting, in a mission which was supposed to be about security, development and winning the hearts and minds of the people, but which has increasingly been bogged down in the south fighting a guerrilla war against the Taleban.