In 2012-13, Lt-Colonel retired, Colin Vaudin commanded Two Signal Regiment in a six-month tour of Helmand Province and Kabul and he did shorter tours on four or five other occasions.
US President Joe Biden has pledged to withdraw all troops from Afghanistan by the end of the month.
Most have gone already with the Taliban now making a rapid resurgence and closing in on the capital Kabul.
‘It’s a monumental failure of grand strategy and global politics,’ said Mr Vaudin.
‘Politicians are trying to re-frame the reason why we went there in the first place and the initial objective to defeat Al-Qaeda but that was done within six months, and the last 19 years have been based on a promise of nation-building and a brighter future for Afghanistan.
‘Potentially, generations of young girls have been condemned to a lifetime of no education or freedoms, and to sexual slavery.’
There was a palpable sense of failure within the military though it was not their fault and some of Mr Vaudin’s former colleagues had told him in recent days of their suicidal thoughts.
‘456 British service people were killed, thousands more were wounded, and there was a huge strain on our families who were left behind not knowing what would happen to us. We feel as if it was almost for nothing and that we have failed.’
Politicians would wring their hands and try and justify it, arguing that the soldiers did not die in vain, but this was a monumental failure of state craft and a betrayal of everyone who fought and died there, he said.
Mr Vaudin said he dreaded to think what the monetary cost had been – people had died and been wounded only to see it all collapse like a deck of cards within barely three months.
‘Who will help the British and Americans when we need it now?’ he said. ‘We now have this brand of global Britain but who will trust us if we walk away from promises?’
He said he was exceptionally proud of the people he fought with – totally ordinary people who did extraordinary things, showing exemplary courage, bravery and dedication.
‘We can be proud of that irrespective of the outcome,’ he said.
Deputy Jonathan Le Tocq, who has responsibility for overseas issues within the Policy & Resources Committee, added his view on Twitter over the weekend.
‘Politics had failed, politicians had failed, democracy had failed and humanity had failed,’ he said.