Hollywood avoided WWI after the armistice, but the success of The Big Parade launched a wave of productions about the war over the next ten years. It was made only eight years after America joined the conflict, so there must have been real life experience on either side of the camera. Though there isn't an overwhelming impression of authenticity.
King Vidor's epic invented a lot of the rules for platoon films, partly because it follows a predictable path: the initial patriotism on the home front; the drilling of a group of civilians into a fighting unit; the boredom of waiting and the virile furlough pursuits. Then the young soldiers confront the German army, and are stopped dead on the western front.
The film is dominated by a romance between its charismatic star John Gilbert as a rich doughboy, and the French Renée Adorée as an exuberant farmer's daughter. The cute comedy of their mutual incomprehension is utterly charming.
The Big Parade gave audiences a vision of war: the fighter planes, the army camps, the anti-aircraft artillery and chemical weapons. A veteran might have felt too many punches were pulled in the interests of tasteful entertainment. It's a long film, but doesn't drag. It was groundbreaking , but better, more incendiary war films were coming.