An MP has asked for a Parliamentary debate on the support for soldiers with post traumatic stress disorder.
Ogmore's Labour MP Huw Irranca Davies raised the case of L/Cpl Darren Gregory of 2nd Battalion The Royal Welsh, from Llanharan, Rhondda Cynon Taf.
He said L/Cpl Gregory's father had told him the Iraq veteran had been let down by support services since returning.
The MoD said delivering mental health services to serving and former service personnel was "a top priority".
L/Cpl Gregory was cited for gallantry for his actions in Basra in 2007, but his father has said he was forced to leave the army because of the stress associated with his time in battle.
Mr Irranca Davies used business questions in the Commons to describe L/Cpl Gregory's actions and to call for a debate to "make sure we have the support for our courageous armed forces".
He told the Commons: "His actions were utterly decisive and he single handedly, inspired the defence to beat off two heavy attacks by superior force and yet, this person, in 2 Royal Welsh, was let down when he needed the support he did need."
Speaking on Radio Wales, he said L/Cpl Gregory was conspicuous gallantry saw him defending his colleagues from an exposed position on a roof top.
He said: "But unfortunately, when he required help and assistance himself, when he was suffering from post traumatic stress disorder, and mental health issues, [the armed forces] weren't there for him.
"He loved his life within 2 Royal Welsh, he would still love to be in there, he would still love to be serving, but unfortunately he's been let down badly."
Mr Irranca Davies said two families in his constituency have sons who have been forced to leave the army because they did not have the support they needed when they were suffering with mental health issues.
He said: "I would like to get to the bottom of this. Let's see if it's something more widespread than the odd individual."
A MoD spokesperson said: "The MoD operates a range of measures to tackle mental health issues among the armed forces.
"In Afghanistan, community psychiatric nurses are on hand to provide any care and treatment needed and two UK-based teams of psychiatrists and mental health nurses are available to deploy to Afghanistan at short notice, if required.
"In addition, there are 15 military departments of community mental health across the UK, which provide out-patient mental healthcare.
"These teams are made up of psychiatrists and mental health nurses, with support from clinical psychologists and mental health social workers.
"A wide range of psychiatric and psychological treatments are available and most patients can be treated near their units."