First there was a loud bang; then we were enveloped in dust that descended like a shroud. “Mortars!” someone shouted.

In a panic, we scrambled for the relative shelter of our vehicle on a hill opposite Musa Qala, a Taliban stronghold under siege this weekend by Nato and Afghan forces, and dived inside.

Sand thrown up by the explosion swirled through the hatches and we reached for our helmets, keeping low in case of incoming fire.

Only when the dust had settled was the horror revealed: the blast had been caused not by a mortar, but by a mine that had been detonated when a British vehicle passed over it. One of the men with whom we were travelling was killed and two others wounded. The dead man’s next of kin were informed last night.

It happened as a British convoy passed along a wadi – a dried-out watercourse – in the desert near Musa Qala. We were standing at the top of the pass and stretching our legs as we waited for troops to recover an Afghan army truck that had got stuck in the sand 25 yards away.

The mine, probably one left by Soviet occupiers in the 1980s, exploded as the British vehicles steered past the truck.

Helplessly, we watched as British and US medics crawled across the Afghan truck to retrieve the casualties from their vehicle, its armour plating twisted by the force of the blast.

The photographer Nick Cornish and I were embedded in the biggest British-led operation staged so far in the Afghanistan war. The aim is to reconquer a swathe of territory that the Taliban has dared to call its own.

Amid heavy fighting, British, Afghan and American forces had been advancing all week towards Musa Qala, a town of 15,000- 20,000 inhabitants in Helmand. The British and Afghans advanced from the south and, on Friday night, the US 82nd Air-borne Division landed with troops to attack from the north.

Yesterday the US soldiers were closing in on the suburbs of the town, backed by Apache attack helicopters and A-10 Thunderbolt jets.

British forces were concentrated on the southern side. Warrior armoured vehicles of the Scots Guards, backed by A-10 air strikes, attacked the village of Deh Zohr-e-Sofia, southwest of Musa Qala, where we had witnessed a violent gun battle on Friday.

We had walked in silence towards the village, two columns of British and Afghan soldiers nervously wondering whether the Taliban would be lying in wait for us behind the high, mud-brick walls. They were.

A burst of gunfire erupted in front and we dived into a shallow ditch for cover. It was no protection, however, and we had little choice but to run. Bullets slammed into the ground around us as, feeling horribly exposed, we raced for the sanctuary of an armoured Humvee.

“We’d be dead by now if they could shoot straight,” said an officer from 2nd Battalion, Yorkshire Regiment, as we took cover, sweating heavily in our flak jackets.

The latest battle for Musa Qala, one of the most fiercely fought-over towns in southern Afghanistan, had begun in earnest and was about to have horrific consequences for a group of refugees attempting to drive through the maelstrom to safety.

Terrifying in its intensity, Friday’s firefight was just one engagement in what officers have described as one of the biggest British military operations since the invasion of Iraq in 2003, with hundreds of troops embroiled.

Held briefly last year by British forces and defended with the loss of seven soldiers, Musa Qala was recaptured by the Taliban in February after UK troops had pulled out during an ill-fated truce.

Last week, in a shift of strategy, Nato forces were moving back into the area, creating a “zone of security” to help win the hearts and minds of the locals. A British officer said: “Our aim now is to take control of no town that we cannot hold on to, unless we can deliver development for the people who live there.”

However, events in Deh Zohr-e-Sofia demonstrated how difficult it is to keep families safe, let alone make friends, in this treacherous corner of the world.

As we got our breath back behind the wheel of the Humvee, we noticed a white car, upturned on the road behind us, blood streaking one of its windows. Nearby, people had gathered around a truck, shouting and gesticulating. Two bodies lay in the dust.

British troops went forward to offer their help, but were turned back by angry bystanders shouting, “Go away,” in English.

Amid the confusion, it took some time for the sequence of events to become clear. But in the end there was no doubt that the two civilians had been killed by American gunfire.

As we had approached the village, the Taliban had fired at us from five or six positions.

Once the shooting began, the refugees in the truck and car tried desperately to escape and had driven past us at high speed. Their flight took them directly towards two US Humvees parked by the side of the road.

The Americans, thinking they were under attack from a suicide bomber, opened fire, killing the driver and a passenger in the truck. Three others were injured: a woman with a bullet wound in her face, a boy who was shot in the arm and a girl with a serious gash in her side. The children were both about five years old.

At first the families were too enraged to let Corporal Phil French, a medic with the Yorkshire Regiment, anywhere near the wounded. Eventually, he gave the woman and children first aid. The British tried to arrange a helicopter to take them for treatment. None was available.

Soldiers tried to make sense of it. “Americans have been the victims time and again of suicide attacks,” said one. Another argued that the civilians had in effect been “human shields” and had been “deliberately forced to drive towards us – probably against their will – and used as a screen to attack”.

Another felt sorry for the men who had pulled the triggers. “They will have to live with this for the rest of their lives,” he said.

The battle went on all afternoon. Later, the British would be thankful to the Americans. As a Humvee kept up a steady barrage in answer to enemy gunfire, American F16s swooped down from above to strafe the compounds in which the Taliban fighters were sheltering.

At one point, an aircraft believed to be a B1 bomber dropped a precision-targeted bomb onto an area where the enemy was gathering for an attack.

It was expected to be a long and bloody battle. For the Taliban, the British attack on Musa Qala had come as no surprise. Leaflets had been dropped on the town, warning residents that Nato forces were coming.

The movement began on Tuesday at first light when Royal Marine commandos stormed across the Helmand river in amphibious vehicles near the town of Sangin. They were soon fending off rocket and machine-gun attacks.

In a manoeuvre nearby, Trooper Jack Sadler, of the Honourable Artillery Company, was killed and two soldiers were injured when their vehicle was caught in an explosion.

British forces had been encouraged in the days before their assault by the public defection to the government side of Mullah Abdul Salaam, a key Taliban commander. He brought with him up to one-third of the fighters who had been defending Musa Qala.

On Wednesday, President Hamid Karzai, who had encouraged Salaam’s defection by pushing for negotiations, sent several dozen militia to the area to help protect the mullah from reprisals. Bizarrely, they arrived at the British lines in school buses that had brought them from Kabul, the capital.

On the same day, a British patrol was attacked near the Kajaki dam northeast of Sangin, resulting in a firefight that lasted several hours and prompted the deployment of RAF Harrier jets to push back the enemy.

To the west, near the town of Now Zad, a company of Estonians backed by Royal Marines came under sustained attack. American special forces were also involved. One heavy Taliban attack was driven back only after a bomb had been dropped on their position from an American B1 aircraft.

RAF helicopter pilots flew two rescue missions, despite heavy rocket fire, to recover two wounded Taliban fighters. “We had British and Estonian lives risked to save the life of two enemy,” said Major Alex Murray.

Danish forces under UK command were attacked in the town of Gereshk; and intelligence suggested the Taliban were trying to move two large explosive devices south to be used for suicide bombs in British-controlled towns.

On Thursday, a big Afghan army column began an advance, backed by British and American special forces, while diversionary attacks were launched on Taliban positions in other parts of Helmand.

Yesterday, as America’s 82nd Air-borne Division advanced on Musa Qala, thousands of civilians were believed to be trapped in the town. The emphasis was on trying to persuade Taliban leaders to flee Musa Qala or defect to the government.

“The prize in this insurgency is the people,” said Lieutenant-Colonel Richard Eaton, a spokesman for the British forces in Helmand. “What we need to do in Musa Qala is persuade the people they will be better off under the government.”

British officers said the whole operation – backed by an Afghan brigade, numerous special forces and more than a battalion of American troops – was so big that some aircraft were redeployed from combat in Iraq.

The Afghan forces were said to be proving their mettle in the latest combat. “These guys have no hesitation in killing the Taliban,” said Lieutenant-Colonel Simon Downey, commanding officer of the 2nd Battalion, Yorkshire Regiment, which is “mentoring” the Afghan troops.

The arrangement was not without frustrations. The Afghans were supposedly fighting under their own command. Yet they could barely function without Nato’s protection and Nato had to cajole them to move forward.

Another complication was the use of cannabis by Afghan soldiers. “Hashish is part of our culture,” said an Afghan officer. “It is just like whisky and wine for you.”

NATO - International Security Assistance Force website

40 Commando Royal Marines webpage

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