The UK has handed control of Camp Bastion in Helmand province to Afghan security forces, marking the end of a military presence in the country that spanned more than a decade and cost 453 British soldiers their lives.
Defence Secretary Michael Fallon has admitted that "mistakes" were made during Britain's campaign in Afghanistan.
"I think the generals have been clear that mistakes were made. Mistakes were made militarily and mistakes were made by the politicians at the time," Mr Fallon told the BBC's Andrew Marr Show.
"Clearly the numbers weren't there at the beginning, the equipment wasn't quite good enough at the beginning, and we have learnt an awful lot from the campaign."
Mr Fallon said there was "no guarantee" that Afghanistan would be "stable and safe" following the departure of western combat troops.
However, he said that British troops would not return to Afghanistan under any circumstances, even if there was a large-scale insurrection in Helmand or Kabul.
The mother of Trooper James Munday, who was killed in Afghanistan in 2008, says the mission's end brings no closure for her or her family.
One girl's reaction to a suicide attack in Kabul has become emblematic of the worst days of the war. ITV News has tracked her down.
Once home to 10,000 troops, all of the UK's armed forces have now left Camp Bastion in Afghanistan.