Omar Khadr, often known as the "al-Qaeda child soldier," has been freed in Canada after 13 years in detention, most of that at Guantanamo.

A Canadian citizen, Khadr was made to fight for al-Qaeda when he was 15. US forces captured him, then sent him to Gitmo, where he was repeatedly tortured.

Omar Khadr's case represented the American treatment of "war on terror" detainees at its worst; his hard-won release is perhaps a symbol of the gradual end of that era.

What happened to Omar Khadr

In 2002, when Omar Khadr was 15 years old, his father enlisted him as a child soldier for al-Qaeda in Afghanistan.

Khadr is Canadian, but his father spent much of the 1990s entangled in jihadist causes, moving the family between Canada, Pakistan, and later Afghanistan. A few months after 9/11 and the US-led invasion of Afghanistan, Omar's father sent him to translate for Libyan jihadists who were training Afghan fighters in bomb-making.

On July 27, 2002, US special forces raided the jihadist camp where Omar Khadr was staying. It at first appeared that everyone in the camp was killed in the firefight, but when one of the Americans inspected the motionless body of a boy with three bullet wounds, they found he was alive. In fluent English, the boy begged to be killed.

Khadr was sent to the US military hospital and then the US interrogation center at Bagram Air Base in Afghanistan, where he was tortured. He was then sent to the prison at Guantanamo Bay, Cuba, which was to be his home for over a decade.

Omar Khadr's torture at Guantanamo

There is a story you most commonly hear in reference to Omar Khadr's torture at Guantanamo: the mop incident. Journalist Jeff Tietz, in his harrowing 2006 investigation for Rolling Stone, described it in disturbing detail.

A few months into Khadr's detention — he was, keep in mind, still only a child — guards chained him to the floor of an interrogation room. They pulled his arms and legs behind in a "bow" position, until his limbs strained painfully at their sockets. This was known in the officially sanctioned American torture guides as a "stress position," and victims often pass out from the pain. Over several hours, the guards contorted Omar into different stress positions, each time shoving him into a painful position on the ground. Eventually, inevitably, he urinated himself.

The MPs returned, mocked him for a while and then poured pine-oil solvent all over his body. Without altering his chains, they began dragging him by his feet through the mixture of urine and pine oil. Because his body had been so tightened, the new motion racked it. The MPs swung him around and around, the piss and solvent washing up into his face. The idea was to use him as a human mop. When the MPs felt they'd successfully pretended to soak up the liquid with his body, they uncuffed him and carried him back to his cell. He was not allowed a change of clothes for two days.

Much of Omar's torture was psychological as well as physical. One interrogator used Omar's youth against him, threatening to send him to a special facility where "they like small boys." Such threats often went with physical torture, as Tietz recounts:

While he was at Guantanamo, Omar was beaten in the head, nearly suffocated, threatened with having his clothes taken indefinitely and, as at Bagram, lunged at by attack dogs while wearing a bag over his head. "Your life is in my hands," an intelligence officer told him during an interrogation in the spring of 2003. During the questioning, Omar gave an answer the interrogator did not like. He spat in Omar's face, tore out some of his hair and threatened to send him to Israel, Egypt, Jordan or Syria -- places where they tortured people without constraints: very slowly, analytically removing body parts. The Egyptians, the interrogator told Omar, would hand him to Askri raqm tisa -- Soldier Number Nine. Soldier Number Nine, the interrogator explained, was a guard who specialized in raping prisoners.

Omar's treatment was not unique at Guantanamo, especially in the early years. But it is all the more horrific for his age.

What Omar Khadr represents about America's war on terror

It is possible to imagine a way in which interrogators and guards could convince themselves, however wrongly, that their torture of other Guantanamo prisoners was permissible or even warranted; that these were "bad guys" undeserving of fundamental human rights and that their torture would protect American national security.

But it is mind-boggling to try to understand how an entire system of American jailers, interrogators, and military overseers could believe that repeatedly torturing a child was both acceptable and worthwhile. That they reached this conclusion, and continued to hold it for years, speaks to the horrors of Guantanamo and the moral black hole into which the Bush administration led the United States.

In a 2003 meeting with Canadian intelligence officials, Khadr broke down in sobs. "Promise me you'll protect me from the Americans," he begged. When they refused, he called out for his mother.

That same year, Army Chaplain James Yee was assigned to Guantanamo, where he was surprised to find Khadr, an English-speaking boy, among the prison's population. Yee later told the journalist Michelle Shephard that he would sometimes see Khadr reading a book of Disney cartoons. An interrogator had presented the book to Khadr during an interrogation, intending it as an insult. In fact, Khadr had been delighted.

Yee recalled finding Khadr curled up asleep on his cot, the book with the Mickey Mouse cover clutched to his chest. It is difficult to picture: a boy on a metal cot finding momentary respite between violent interrogations, grasping this lone symbol of a childhood he never had.

In 2010, after Khadr had spent nearly a decade in Guantanamo and was now in his early 20s, a psychologist who was visiting the prison asked him what he most missed about life before his captivity. He replied, "Being loved."

Omar Khadr's path to freedom

Throughout his detention, international rights groups and the United Nations called repeatedly for Khadr's release. He was a child soldier, they said, and under international law should be considered a victim of his recruiters who was acting under coercion, not of his own volition.

The US rejected this, and accused Khadr of throwing a grenade that killed a US soldier during the July 2002 firefight. (The merits of that allegation remain a source of considerable controversy.) He was the first person since World War II prosecuted by a military tribunal for war crimes committed while he was a juvenile.

In 2010, he pleaded guilty, later explaining that he did so only because he saw no other path to freedom. The US had a strong incentive to pursue a plea deal: a number of its Guantanamo cases had gone poorly, and had the government pursued and lost its case against Khadr, it may have set a precedent on issues relating to evidence that would have imperiled a number of other US military commission cases.

The plea deal allowed Khadr to be transferred to a Canadian prison in 2012. He was transferred between a series of prisons in Canada through 2014 as he began appealing both his case and his earlier guilty plea. On April 24, 2015, a Canadian judge granted Khadr bail — at the Canadian government's objection. On May 7, the judge overruled the government's objections and ordered him freed.

Omar Khadr's life after captivity

As of Thursday, Khadr had been released on bail, and will live with his lawyer and his lawyer's wife in Edmonton. That comes with substantial restrictions: he must wear a monitoring bracelet and submit to extensive monitoring, is not allowed to possess a laptop or cellphone, and is under curfew every night.

Khadr spoke to reporters in Edmonton on Thursday. He expressed gratitude and humility. "I would like to thank the Canadian public for trusting me and giving me a chance," he said. "I will prove to them that I am more than what they thought of me."

In the video, one of the reporters asks Khadr about his father, who had sent young Omar into service as a child soldier and was killed in 2003 by Pakistani security forces. "There's a lot of questions I would like to ask my father," he says. "A lot of decisions that he made, reasons he took us back there, just a whole bunch of questions about his reasoning, his life decisions."

Another reporter asks Khadr, "What do you want to do most?" He smiles. "That's a hard question. Everything, and nothing in particular. Everything." He suggests he might like to work in health care.