During World War I, John was attached to the Canadian forces as a war artist and made a number of memorable portraits of Canadian infantrymen. The end result was to have been a huge mural for Lord Beaverbrook and the sketches and cartoon for this suggest that it might have become his greatest large-scale work. However, like so many of his monumental conceptions, it was never completed. As a war artist, he was allowed to keep his facial hair and therefore, he and King George V were the only Army officers in the Allied forces to have a beard. After two months in France he was sent home in disgrace after taking part in a brawl. Lord Beaverbrook, whose intervention saved John from a court-martial, sent him back to France where he produced studies for a proposed Canadian War Memorial picture, although the only major work to result from the experience was Fraternity. In 2011, the Duke and Duchess of Cambridge finally unveiled this mural at the Canadian War Museum in Ottawa -‘The Canadians Opposite Lens’. This unfinished painting is 12 feet high by 40 feet long.