THE hardest part of Jason Poole’s day is his early morning confrontation with the face staring back at him from his bathroom mirror. In the past 18 months, plastic surgeons have rebuilt it five times.

“I used to be handsome, you know,” says the 23-year-old US Marine, who was on foot patrol in western Iraq in June 2004 when he suffered terrible injuries in a roadside bomb blast. He adds: “But hey, c’est la vie.”

He has earned a Purple Heart medal for valour, but the twist to this Marine’s story is that when he fought in Iraq he wasn’t American at all, but British. Born in Bristol, he moved to California with his parents at the age of 12, and signed on the dotted line aged 17 in exchange for help from the Marines with college tuition fees and his application for US citizenship.

Corporal Poole cannot remember the explosion itself. He was in a coma for two months and is permanently brain-damaged. Two Iraqi soldiers and an interpreter were killed, but the Marine’s body armour saved him. He is now deaf in one ear and blind in one eye, and his face is a maze of skin and bone grafts held together with metal plates. Shrapnel was embedded in his skull and his brain injuries were so severe that he has had to learn to walk and talk again.

“We are talking about a brain-injury epidemic,” says Nurse Jill Gandolfi, who cares for Corporal Poole in a rehabilitation unit run by the US Department of Veterans Affairs in Palo Alto. The official number of brain- injured Iraq veterans is more than 1,700, but Harriet Zeiner, Palo Alto’s leading neuropsychologist, believes that well over 6,000 such injuries is a far more realistic estimate.

Pentagon figures indicate that, of more than 16,000 US troops wounded in combat in Iraq, 11,852 were injured by bombs, mortars and grenades.

Improvements in both body armour and battlefield medicine mean that Operation Iraqi Freedom boasts the highest survival rate of any war; up to eight for every death. But survivors such as Jason are coming home with more complicated head injuries caused by shrapnel wounds and shockwaves from bomb blasts; a growing army of brain-damaged servicemen and women, largely hidden from public view.

“It gets missed, they get discharged and go home,” says Dr Zeiner, who complains that brain scans are still not routine for soldiers surviving explosions and that the problem is often never diagnosed.

Lt. Col. Garry Venable, a Pentagon spokesman, said: “There are an awful lot more soldiers alive (after such incidents) than ever before.” He was unable to comment on the figures.

“Basically, it sucks,” says Corporal Poole, as he waits in blinding sunshine for his bus to the Palo Alto unit, one of four specialist “polytrauma” centres created by the US Forces.

About 800 patients have been treated in these centres so far. Researchers at Harvard and Columbia universities calculate that the total cost for treating brain injuries from Iraq will exceed $14 billion (£8 billion) over 20 years.

Though the corporal has had hundreds of hours of therapy, he can barely manage to read more than 20 words a minute. “He can think of things to say but he can’t get them out,” says Nurse Gandolfi.

“Americans need to know what the cost is to the people fighting,” says Dr Zeiner. “It’s not just the dead, but the injured. People like Jason have to reinvent who they are.”

Times Recommends

• No cause for celebration in crushed Sarajevo
• Jazz funeral for the final victims of Katrina
• French fined for 'insulting' civil servants