On April 13, 2004, Second Lieutenant Melissa Stockwell was leading a United States Army convoy of supply vehicles through Baghdad. She had been assigned a new route that took them from the green zone, the fortified international area in the city centre, and a test run was planned. The excited 24-year-old from Minneapolis, Minnesota, had rung her parents the evening before to tell them of her new responsibility.

The Humvee had no doors and Stockwell sat behind the driver with her left leg hanging outside so that she could use her rifle more easily. Ten minutes into the journey, they passed under a bridge and all hell broke loose.

Stockwell remembers someone shouting: “We hit an IED [Improvised Explosive Device], we hit an IED.” The Humvee swerved left, bounced off a guardrail and smashed into a house. Stockwell looked down and saw blood all over her trousers. She was treated at the scene and then rushed to the army hospital.

The next thing Stockwell remembers is waking from surgery. The first person she saw was her husband, Dick, also a serving officer in Iraq. “I think something happened to my leg,” she recalled saying to him. Her husband reached for her hand and said: “It's gone.”

Stockwell was flown back to the US, but in hospital an infection set in. She endured 15 surgeries and 20 blood transfusions and was at one point close to death. All that was left of what she calls her “little leg” was six inches of bone and muscle.

It says something about Stockwell that only four months after being taken to the Walter Reed Army Medical Centre in Washington, she completed the New York City Marathon on a handbike.

A year after her misfortune, Stockwell was out of the hospital and began swimming. She said that she wanted to go to the Olympics as a gymnast when she was a child, but had not been a strong swimmer. “I was drawn to swimming because I didn't have to wear a prosthetic to do it,” she said.

For most people, it might have looked like pure rehabilitation work, but for Stockwell it was developing into an unlikely dream. The US Veterans Paralympic Performance Programme learnt of Stockwell through its links with the army hospitals and monitored her progress with interest.

Three months later, she took 17 seconds off her personal best in the 400metres freestyle, finishing in 5min 3.08sec to smash the national record at the US Paralympic trials. Stockwell, now 28, looks forward to that event on Friday in Beijing, but, with Natalie du Toit, the South African, who swam in the Olympics, leading a competitive field, a medal would be another significant achievement.

If she does get on to the podium, she can add her medal to the Purple Heart and Bronze Star that she was awarded by the US Armed Forces respectively for being wounded in action and for heroic or meritorious service. “You go to Iraq and you defend the country in uniform,” she said. “And here I am in a different uniform representing the same country.”

Sixteen of the 213 athletes on the US team are Service veterans; Stockwell is one of two, the other being Scott Winkler, injured in the line of duty in Iraq. Many others did not make the team this time, but can look forward to London 2012.

The roads to the Paralympics are many and varied, but one has always been by way of war. The Paralympics grew out of the Stoke Mandeville Games, an annual competition that Dr Ludwig Guttmann founded in 1948 as part of the rehabilitation of wounded servicemen. But it has older antecedents. Crowds turned out in London to watch the men of St Dunstan's, a hostel for blind former servicemen from the First World War, compete in their Saturday Sports.

Yet Great Britain has long since lost the link with the Army. The presence of servicemen in the team has come from individual rather than team initiative. Alan Ash, a former Royal Marine and part of the wheelchair rugby team, is the sole British serviceman.

“The Armed Forces have created a programme called ‘Battleback' that has grown out of the work we've done,” Phil Lane, the British Paralympics Association chief executive and chef de mission in Beijing, said. “It's wider than just Paralympic sport and will be based out of Headley Court [the Defence Medical Rehabilitation Centre, near Epsom, in Surrey].”

But Battleback was not set up until July and may have come too late to benefit those aiming for London 2012.