US Army 7th Field Artillery troops fire mustard gas shells at the enemy at Varmaise in Oise France during World war I.

World War I footage showing use of mustard gas. US Army 7th Field Artillery troops fire mustard gas shells at the enemy at Varmaise in Oise France on July 5, 1918 during World war I. The artillery crew wear protective gas masks. Shows US soldier in a trench wearing gas masks. Distant mustard gas explosion. Troops in trenches wearing masks, fire at the enemy.