"HE told me he came upon German soldiers who had been crucified on barn doors.

He would never elaborate on that. I know it lived with him for the rest of his life."

The poignant and, at times, tragic and horrible memories of the descendants of Scottish soldiers who fought on the frontline in First World War have been brought to life in a powerful new documentary.

Britain and Germany went to war against each other 100 years ago tomorrow on August 4, 1914 and this week officially begins four years of commemoration of the Great War across the UK.

In her film Still Sounds: The Great War, Glasgow-born artist Margaret Moore captured the memories of the children and grandchildren of the soldiers, now in their 70s and 80s.

They include Bill Everitt, 75, whose grandfather Robert Beattie joined the Royal Highlanders in his mid-20s. Everitt's grandfather's story of the brutal crucifixions is one of the details of the war Moore captures.

TWO black-and-white photographs of a soldier sit side by side.

In one, a cheerful young man looks at the camera. In another, the same man has aged what looks to be 10 years, staring bleakly through eyes which are haunted, hollow and tired.

"That's him two years later," said Henry Couper, 84, whose father, John, served with The Cameronians (Scottish Rifles) after signing up in 1916. There's such a change in his appearance. He was worn down … That's what the trenches did. They wore him down."

Couper's father, born in Dunfermline, died in 1936, when his son had been at Scotland Street School, in Glasgow's southside, for only a year. He is one of six former pupils whose memories of their fathers and grandfathers have been brought together for the unique documentary by Moore.

He recalls snippets of information gleaned from older relatives, documents and photographs.

Couper was told how his father, after six weeks of training in "how to use a rifle and march about" left Glasgow's Central Station, waved off by his wife and daughter.

Strolling up the platform, he bade the city farewell with the words: "I'm away to fight for all you buggers!"

Couper, a former sound engineer with STV in Glasgow, also has a tatty Christmas card, sent to "Uncle John with love", from his nephews James and David Wilson.

"My father carried that all through the war," he said. "He put a list of the battles he fought and sent it back to them after the war."

Bill Everitt, 75, remembers sitting on his grandfather Robert Beattie's knee while he regaled him with three favourite war songs.

"I was six or seven," he said. "He would sing The Galloping Major, What A Lovely War and Whiter Than The Water On The Wall.

"He said when the conflict was on he would be in a restaurant in Glasgow and it was not uncommon for women to put a white feather on his table. So he signed up with the Gordon Highlanders when he was 25 or 26."

Beattie was wounded not long into his service. "He went to help an officer whose backpack was on fire," Everitt said. "He ran up to get the pack off and he took a hit. He saw something hit his elbow and he couldn't move. The officer was dead.

"The next thing he remembered was being on a stretcher in London."

Doctors wanted to take his arm off, Everitt said, but he pleaded with them to keep it. "He was left with half an arm."

Everitt's grandfather talked of seeing corpses littering the trenches.

"Another time, they came upon German soldiers who had been crucified on barn doors. He wouldn't ever elaborate on that.

"I know it lived with him for the rest of his life," said Everitt.

Alex McKinlay's father Peter, born in Glasgow in 1896, was 18 when he volunteered.

The 87-year-old said: "He was in barracks in Aberdeen - the same ones I went into when I did National Service. We have that in common."

McKinlay's father, who was in the Battle of the Somme, was shot in the abdomen and lost a finger.

"It bothered him for the rest of his life," said McKinlay. "He was taken to a field hospital and they reattached it but in winter the wound would open up. He couldn't get any relief."

He has photographs showing his father in full dress uniform, from 1915 or 1916.

"My father didn't talk much about the war. Whenever you broached the subject he didn't want to recall it. What I gleaned about it was what I saw, like his finger. I know he had problems with his health. He had breathing problems from when he was gassed."

James O'Neill's father Hugh, who served with the Scots Fusiliers, "used to sit with his leg on the kitchen table", he remembers.

"He had two holes in his knee from shrapnel. You could see the holes. He would put a big cotton patch over his knee."

He has photographs showing Hugh O'Neill in military uniform and letters sent to his sweetheart Jennie, who he later married.

His father's leg injuries eventually resulted in him having the limb amputated, said O'Neill, 85. "He had a stump but he walked about for many years," he said. "He managed all right and used a stick."

Filmmaker Moore, who is fascinated by the social history of Glasgow, said filming the reminiscences of the soldiers' descendants was an emotional experience.

"Even after all these years, it's amazing how much they remember," she said. "I found all their personal stories fascinating."

The Still Sounds: The Great War project, which was funded by Moore, an independent artist, was a "natural progression" from an installation she did at the Scotland Street School Museum last summer.

Still Sounds Scotland Street 2013 interwove threads of local family history, through school experience in Glasgow, using recorded conversations of former pupils layered with the sounds of schoolchildren today.

"Two of the former school pupils I interviewed for that project showed me photographs of their fathers who fought in the First World War," Moore explained.

"They know I'm interested in history and I wondered if there were other former pupils with fathers and grandfathers in the war and what their memories were of them."

London-based Moore, who works in sculpture, photography, video, and installations, has her roots firmly in the once-busy residential area of Tradeston, although she did not attend the Charles Rennie Mackintosh-built Scotland Street School, which closed in 1979.

She has passed her interest in history to her daughter, Alex Moore, who did illustrations for the documentary. It is screened on a loop at the Burrell Collection in Glasgow from August 15 to October 18. Entry is free. It is not suitable for young children.