British troops handed responsibility for security in the capital of war-torn Helmand Province to Afghan forces today.
The milestone transfer of control of Lashkar Gah to Afghan soldiers and police marks a step towards the planned pull-out of UK combat forces in Afghanistan by the end of 2014.
Afghan security forces are taking charge of seven districts across the country this week as part of moves towards the ultimate withdrawal of Nato troops.
But the handover of Helmand's capital is particularly significant because the province remains volatile and dangerous more than five years after British forces were first deployed there in spring 2006.
Security has improved significantly in Lashkar Gah but concerns remain about the strength of the Taliban and corruption and incompetence among the Afghan army and police.
Seven Afghan police officers were killed by one of their colleagues at a checkpoint near Lashkar Gah on Monday.
Helmand's governor Gulab Mangal paid tribute in an open letter to the bravery of UK forces who have served in his province.
He also recalled meeting Lucy Aldridge, whose son Rifleman William Aldridge, 18, from Bromyard, Herefordshire, was one of five British soldiers killed in a double Taliban bomb attack in July 2009.
"I said to her, 'one day you will come to see what your son made possible'," Mr Mangal wrote.
"The government and the Afghan forces in Helmand will keep this promise for Mrs Aldridge and all the families around the world who have sacrificed for us. We will lead security and lead Afghanistan to a better future."
Afghan soldiers and police have been assuming responsibility for keeping Lashkar Gah safe over recent months and today no Nato troops are involved in the day-to-day security of the city, the Ministry of Defence said.
British forces will remain in other parts of central Helmand province and continue efforts to build up the Afghan National Security Forces (ANSF).
Defence Secretary Liam Fox stressed last month that the handover of Lashkar Gah did not mean UK troops would come home early.
He said today: "The Afghan National Security Forces have proven they are capable of delivering security to the local people of Lashkar Gah, and today's ceremony recognises this.
"The ANSF already provide security in Lashkar Gar and the capacity of local government is improving, both of which are allowing normal life to return to large areas of the municipality.
"All of this means we have a solid base to build on as we work with our Afghan and international partners towards full transition - security, governance and development - over the coming years."
There are currently about 9,500 British troops serving in Afghanistan, the majority of them in Helmand.
A total of 377 UK servicemen and women have died in the campaign since the start of operations in 2001.
The other areas being passed to Afghan security forces are the provincial capitals of Herat, Mazer-e-Sharif and Mehterlam, all of Bamiyan and Panshir provinces and most of Kabul Province.