Daniel Radcliffe stars in WWI TV film

Harry Potter star Daniel Radcliffe cannot imagine what it was like to live amid the stench of death in the trenches of World War One -- but he says his generation should never be allowed to forget.

"I think it is as relevant today as it ever was with young men all over the world still sacrificing their lives in the name of war," said the teenage actor critically acclaimed on Monday for his portrayal of writer Rudyard Kipling's doomed son.

Casting off his teenage wizard's cloak, Radcliffe starred in "My Boy Jack" which was screened on British television to mark the annual wartime Remembrance Day and is also the subject of an exhibition at London's Imperial War Museum.

"Radcliffe created an entirely convincing sense of a young man trying unconvincingly not to be scared," The Daily Telegraph said of his performance. "He was well cast," The Independent critic wrote.

Writing the introduction to the first exhibition ever dedicated to the young soldier, Radcliffe said "I can't even begin to imagine what it must have been like in the trenches living amongst the stench of death and knowing that at any moment it may be your last."

Rudyard Kipling, whose "Just So Stories" and "The Jungle Book" have become children's classics, was a fervent propagandist for the war.

He used his influence to ensure his son was able to sign up despite being twice rejected for being severely short-sighted.

The film and the exhibition trace Kipling's progression from gung-ho patriotism to heartbroken disillusionment that ended with him penning the famous lines:

"If any question why we died

"Tell them, because our fathers lied."

On display in the exhibition is Jack's last letter before going over the top in 1915 to meet his death at the Battle of Loos. It was just after his 18th birthday.

In a hastily scrawled message to his parents and sister, he wrote "Funny to think one will be in the thick of it tomorrow."

"This will be my last letter most likely for some time," he said. Two days later, he was dead.

Alongside his note are messages of condolence to Rudyard Kipling from President Theodore Roosevelt and Sherlock Holmes creator Arthur Conan Doyle who both lost sons in the "war to end all wars."