In the aftermath of al-Qaeda's attack on the Twin Towers in 2001, which claimed almost 3,000 lives, coalition forces, led by the US and British, invaded Afghanistan and seized control of the country from the grips of the Taliban.
It sparked a brutal and bloody war that lasted 20 years, which saw thousands of soldiers, aid workers, journalists and civilians lose their lives.
And last month, the US pulled its final troops out of the country, declaring an end to the conflict, with the Taliban scything their way through towns and villages and entering the capital, Kabul.
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Scenes from the airport there, of people desperately clinging onto the sides of planes to escape the returning regime and of women and children begging for help, horrified the world and have led many, including veterans, to question what it was all for.
But Colonel Richard Kemp, who was head of the British operation in Afghanistan in 2003, tells LADbible that the tragic loss of life and the devastating injuries suffered by the men and women, both physical and mental, were not a waste.
"The actions of members of forces and diplomats, aid workers etc. in Afghanistan, were not not in vain, they were not wasted," he says.
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"The hundreds of British soldiers who were killed or British forces members who were killed fighting in Afghanistan, their immense sacrifice was not in vain. Nor was in vain the the very large number of people who have suffered life-changing wounds.
"The reason I say that is because we weren't out there to rebuild Afghanistan, we weren't out there to turn it into Surrey, or anything of that sort.
"We were out there to fight against al-Qaeda and the Taliban to prevent Afghanistan from again becoming a safe haven for terrorists.
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"The reason we deployed in the first place was to get al-Qaeda and the Taliban out of Afghanistan following 9/11, which was the worst terrorist attack the world has ever seen.
"Some people tend to forget that more British people were killed in the Twin Towers than have ever been killed in any single terrorist attack anywhere in the world in history."
Since 2001, 69,000 Afghan security forces and at least 51,000 Afghan civilians have been killed during the war, as well as over 3,500 coalition deaths, including over 2,300 members of the US military and 457 British soldiers.
Col Kemp believes that this immense loss has not only helped protect people in the UK and elsewhere but also allowed for a period of stability in Afghanistan, with new hospitals, roads and schools being built, and over three million young women and girls being given access to education.
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He says: "When I first went to Afghanistan in 2003, just a couple of years after the initial invasion, people across the country were extremely pleased and happy that we were there, that they'd been freed from the shackles of the Taliban.
"They were optimistic for the future. They had promises from us of a better life, of greater freedom, democracy, girls going to school - I visited several schools where girls were present, which was something that hadn't been the case before.
"Those who were killed and wounded, their sacrifice enabled other people back here to live, because undoubtedly, without their presence, there would have been a number of probably very serious terrorist attacks launched from or inspired by jihadists in Afghanistan.
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"So no, I don't think it was wasted."
Sadly, however, Col Kemp says that the 'political will' to continue the efforts in Afghanistan and prevent terrorist cells from flourishing there has now vanished, which he says is a betrayal of those who gave their lives.
He adds: "I certainly feel that the Afghan people have been let down the American people and that Britain and other NATO countries who've contributed so much and fought so hard and sacrificed so much, I think they've all been let down.
"And also, I think that the world's now a less safe place for many reasons as a result of this withdraw."
Topics: War, terrorism, military, World News, UK politics, US News, Politics