Some veterans say they have been left unable to work

"It is also what their masters should expect and they should provide for this exposure to the horrors of war.

"In a sentence we say they did not."

If the government loses, it could face a compensation bill in excess of �500m.

The court heard there are "special pressures" on service life.

"In battle they face unimaginable stress, stress to a level which one cannot understand without a conscious effort or without experience," said Mr Irwin.

'Blot on escutcheon'

"They are facing an occupation which carries psychological and psychiatric risks at the most extreme end of the spectrum."

Mr Irwin said the effects of wartime combat on the individual had been well documented for many decades - particularly since World War II.

He quoted from a 1945 analysis of the mental effects of war, including shell-shock which caused ex-combatants to seek shelter in a phobic reaction to loud noises or flashes of light and left them unable to handle their anxieties.

Mr Irwin suggested that the MoD's "systemic failure" to deal with the problem was partly due to a "macho" culture within the forces towards psychiatric problems.

Some commanders felt it was a "blot on their escutcheon" (stain on their honour) to have mentally injured men under their command.

The case continues.