The Two Worlds of Charlie F is playing in the largest venue at the Pleasance and features the soldiers themselves, on stumps and crutches, in wheelchairs, battle fatigues and shell suits, recounting their personal stories, what happened in action and how they dealt with, and continue to deal with, their terrible misfortune and experiences.
The piece is part documentary, part theatre - there's an extraordinary dance and wheelchair ping pong sequence set to the music of the "Elvira Madigan" Mozart piano concerto - and part hilarious foul-mouthed banter.
And as the soldiers mingled with guests and other fringe performers and personnel beneath the glorious colours and gold leaf decoration of the gallery, you could sense a feeling of relief that so many taboos had been broached and so much steam of bitterness and resentment let off.
The show, which has been scripted by Welsh poet Owen Sheers and directed by Stephen Rayne, started, of all places, at the Theatre Royal, Haymarket in London under the auspices of the Masterclass Trust, and all involved - chairman Arnold Crook, director Nigel Everett, development board member Jeanne Mandry, programmer Hazel Kerr and producer Alice Driver - had made the journey north to cheer on their baby.
This Bravo 22 Company project - the company comprises 30 Wounded, Injured and Sick (WIS) personnel, as well as professonal actors and the production team - also gives the best insight to British army life since Willis Hall's The Long and the Short and the Tall (a play set during the Korean War and once starring Peter O'Toole).
It's not just the disabilities of the soldiers we hear about, but their culture, their camaraderie, their drinking and letter writing, their reasons for joining up ("The Twin Towers went down and I joined to help sort it out"), the smell and the dust of Afghanistan, their deep aversion to silence in recovery, their loved ones.
Music and theatre as part of a rehabilitation process after war is an increasing phenomenon, and is already light years away from the silence that descended on injured and disabled servicemen in the First World War.
People like my shell-shocked grandfather were simply put in hospitals or homes and left to the care of nurses and nuns. Society ignored them. Even their own families ignored them.
So the two worlds of Charlie F must become the one world we all inhabit, that's the message. And in its own small way, the party after the first performance was a hint that this is a real possibility. Joyous, defiant and determined are the only words to describe the occasion, onstage and off.