The Menin Road, 1918

Archival film of the Menin Road in the Ypres Salient, one of the most heavily fought-over stretches of the Western Front.
The Menin Road ran east out of Ypres toward the German lines and was shelled almost continuously for four years. Film like this was shot by military cameramen and is now held by the US National Archives as public-domain government record. It shows the conditions in which the medical and relief services of the war had to operate. Read the full story in our article on The Humanitarian Front: The Role of the Red Cross in World War I.
Public domain — source (US National Archives (via YouTube)). Free to reuse under the stated licence.