By Alastair Leithead
BBC News, Afghanistan
British troops have arrived in southern Afghanistan and made their first contact with the enemy in Helmand province. Alastair Leithead relates the account of soldiers who were on a reconnaissance mission when they received a request for assistance.
The British Army is supporting Afghan forces
When the urgent call came to help the Afghan National Police in a little town called Musa Qala in northern Helmand, the small British platoon was out on a reconnaissance mission.
They reacted quickly, moving in their heavily armed, if not well protected vehicles.
That night they camped just outside the town, and at first light they knew the police were under fire and moved in to help.
The Afghan security forces had taken on more than 300 Taleban fighters and fought through the night.
The police still held their ground but 13 of them were dead, another seven injured.
The British offered medical help, but it was the aircraft - a huge bomber skimmed the rooftops - that gave the Taleban the fright and the police the confidence they needed to gain the advantage.
The Taleban took flight and the police took up the trail, with the British Pathfinders, a specialised force one step below the SAS, moving with them.
This, the British commanders in Afghanistan say, is the way this operation in southern Afghanistan will be run - supporting the Afghan forces, not just doing the fighting for them.
They pushed north through difficult terrain to Baghram, with a few shots fired here and there, but eventually the British troops stepped forward and made themselves heard.
They were admiring their progress, but warned they had come far enough and should drop back to avoid being overstretched and exposed.
It was on the road back near the village of Paysang that the Taleban were waiting for them.
The British platoon saw the signs, indicators they had picked up in Northern Ireland, like the people sitting on the high-points as look outs.
"Things were just a bit out of place and we thought something was wrong," a captain told me.
In the narrow gorge the fighting started, the quick thinking of the experienced British troops had taken away the element of surprise, but the police still took casualties. One dead and six injured.
It was here British troops fired their first shots at Taleban positions, warning shots, but a signal this UK mission to Afghanistan is now properly under way.
Another fly-over, this time from French aircraft, and the fighting again came to an end.
The Army is working closely with security agencies
Chasing an enemy that blends in so well to the background will not be easy, and it is unlikely the British troops will always take such a back seat.
But this is what they have come to Afghanistan to do, help the government bring security back to places where it has no real control.
Working closely with the national security agencies is the way they believe security can be made sustainable.
Since last week's clashes the British have been helping the police shore-up their security, set up patrols and meeting the local elders to reassure them the coalition is here and here to help.
One anecdote I heard a few times from the mission was the family loading up a boat in Musa Qala and heading off down the river.
The soldiers asked why they were going.
"Because the Taleban fighters are here and it is no longer safe to stay in our home," the head of the family replied.
When they were told the British troops had arrived and were setting up in the town they pulled their belongings together and headed back to their house.
Making your presence felt is a big step, following those promises up is an even bigger one, and with so much ground to cover with just a few thousand troops it is going to be a long summer.