By Nick Triggle
BBC News health reporter
Sgt Brennan was injured in October 2004
Thousands of military personnel are injured each year while they are serving.
After hospital treatment, they often need help regaining their fitness before going back to active service.
For the first time, the military's rehabilitation HQ has opened its doors.
When Sergeant Michael Brennan regained consciousness in hospital he was not aware he had been injured in combat.
"I though I had flu," he said.
But the truth was very different. The 25-year-old had been hurt in a suicide bomb attack and lost the bottom of both his legs.
"My biggest fear was that I was going to be on my own because my wife would leave me," said the father-of-three. "I was not the same man I was when she married me.
"But she has been a complete rock. I don't know what I would have done without her and the rest of my family."
Sgt Brennan was attached to a bomb disposal team supporting the Black Watch at Camp Dogwood, near Baghdad, last autumn when the attack occurred.
Now - nine months on - he still does not remember exactly what happened.
Instead, he is looking forward. At the end of the month he will undergo an operation to take muscle from his back and place it at the end of what remains of his legs to allow him to walk on prosthetic legs without his skin ripping.
He will then face months of rehabilitation at the Defence Medical Rehabilitation Centre as he tries to get used to his new legs.
REHABILITATION CENTRE STATISTICS
Some 1,600 patients are admtited each year, 7% of which have been hurt in combat
Another 4,000 are treated as outpatients
Injured service men and women stay for a month on average, although the most serious cases can spend over six months at the unit
Sgt Brennan, who has been receiving physiotherapy and doing exercise programmes at the Surrey base over the last few months, is just one of 1,600 patients admitted each year after receiving hospital treatment.
Another 4,000 military personnel are treated as outpatients and hundreds more treated in outreach clinics.
The centre was first started after World War II for RAF personnel, but in 1996 became the main UK military rehabilitation centre for all three armed forces.
Only 7% of the inpatients are admitted for combat related injuries - a recent one of whom was Private Johnson Beharry, the soldier awarded the Victoria Cross for his service in Iraq.
Instead, the 220 staff at the centre, based in the grounds of a stately Victorian home, spend most of their time treating men and women injured in road crashes or who have suffered muscle and bone injuries from sprained ankles to broken limbs.
As well as having trained consultants and physiotherapists, the Ministry of Defence-funded centre also has psychologists and social workers on hand to help treat depression and other psychological problems that can develop following injuries sustained while in service.
The unit also has specialist neurology facilities and from the autumn will become the armed forces' main base for dealing with amputees such as Sgt Brennan.
Major Andy Neaves, who is in charge of the day-to-day running of the 170-bed centre, said the aim was to provide a centre of excellence for military personnel who have lost limbs.
"Historically, they have been treated in NHS institutions, but that is changing. We want to make sure personnel are treated and given all the support they need by the military. It is a duty of care."
And - understandably after criticism in the past that the military do not do enough for service men and women injured in their work - officials at the base are keen to stress this responsibility.
1,600 patients are admitted to the base each year
Commanding officer Lieutenant Colonel David Minden said: "For most patients we hope they will get back to operational level and want to return to active service.
"For some it may not be possible or they may not want to. But it is important we do all we can for our personnel. It is not about sympathy or convalescence, it is rehabilitation."
All patients - except the ones with the most serious limb and neurological injury - undergo daily exercise programmes often involving 10 half-hour sessions in the gym, pool and exercise hall.
Therapist Sue Sharp said: "It is important to get people back in condition and the way that is done is to make sure they exercise and work the injured joints and muscles. Gone are the days when we let people rest, hoping they will recover."
The tactic has certainly helped Corporal Scott Garthley, 37, who was injured in a scud attack just south of the Kuwait border at the beginning of the Iraq war.
He said: "I suffered also sorts of injuries, shoulder, stomach, spine, head. When I regained consciousness I couldn't move.
"I have spent the best part of two years here doing remedial, occupational therapy and physio and together the three have been great.
"I am now a normal human being again, although I still do have a little pain, but when you compare that to the injuries I received it is amazing."