The soldiers in the March of the Dead sequence were real soldiers on leave from the front. Most of them were killed within the next few weeks.
Director Abel Gance managed to secure the enthusiastic support of the wartime French government by presenting this anti-war classic to the relevant officials as a fervently patriotic film. Not until an official watching French soldiers form ranks to spell out the film title for the opening credits did anyone in the French government bother to ask who or what the film accused. Gance's answer: "The war and its stupidity."
Filmed in part on the battlefield of St. Mihiel, during battle.
Re-edited into a shorter version entitled I Accuse (1921), intended for American audiences, with a less universal anti-war slant and a more anti-German stance, and with a happy ending.
For its original US release, footage of then President Harding, who was involved with a post war armaments treaty, was added with a dedication to his ongoing work.
Blaise Cendrars: the assistant director for the film had joined the French foreign legion during WWI (he was a Swiss citizen) and lost an arm in the battle. He can be seen playing at the end of the movie when the dead soldiers stand up.