The UK has handed over control of Camp Bastion to the Afghan National Security Forces (ANSF).
The Regional Command (South-west) has ceased combat operations in Helmand, with a ceremony at the Bastion-Leatherneck complex, paving the way for the final security transfer to the Afghan military.
The UK has had a military presence in Afghanistan since October 2001, following the 11 September 2001 terrorist attacks in the US. Since then, 453 UK soldiers have died in the 13-year mission.
UK Defence Secretary Michael Fallon said: "Our armed forces' tremendous sacrifice laid the foundations for a strong Afghan Security Force, set the security context that enabled the first democratic transition of power in the country's history and stopped it being a launch pad for terrorist attacks in the UK.
"Although we are ending a significant chapter in our shared history, the UK's commitment to support Afghanistan will continue through institutional development, the Afghan National Army Officer Academy and development aid."
RC (SW) deputy commander and the senior UK officer in Helmand, brigadier Rob Thomson said: "The formal end of UK combat operations in Afghanistan marks the final step in a deliberate, responsible and measured handover to the ANSF.
"They are more than ready to take on responsibility for security in Helmand."
The UK moved its efforts to southern Afghanistan in 2006, with the establishment of Task Force Helmand in April of that year to combat growing insurgency in the region.
In recent months, UK troops, along with the International Security Assistance Force (ISAF), have focused on training and mentoring Afghan soldiers.
Having assuming lead responsibility for security across Afghanistan in June 2013, the 330,000 strong ANSF has been responsible for 99% of operations, including the security for the successful presidential elections in April.
Image: The Union Jack and Stars and Stripes are lowered for the last time at the Bastion-Leatherneck complex in Helmand province, Afghanistan. Photo: © Crown copyright.