Commercially-produced stereoviews  from the First World War  (as produced by Keystone in the USA, Realistic in Britian  and Verascope in France) became  very popular as a record of the war. See The Great War in 3D for a summary of the range by nation. Compact stereo cameras of the Richard Verascope type  were also used to take personal souvenirs. Officially, these were banned but  were widespread in the French and Australian armies. Around half of the Australiians at Gallipoli are thought to have carried cameras.  In November 2017, I purchased a Verascope from a well-known online auction site.  The magazine contained nine developed stereo negatives on glass slides,  which can be dated to 1917.  These were then scanned at 1200dpi and turned into positive images which are unlikely to have been seen for 100 years.  They included scenes from  what seems to be a French aircraft workshop, with French officers giving a tour to  Imperial Russian officers, and a parade in which US flags are displayed.  Two officers feature in most of the photographs, suggesting that these were taken as personal souvenirs.  As the Verascope used glass negatives these were clearly  susceptible to damage during the war and  they are rarer than the commerical stereoviews that comprise prints mounted on card. Examples of single images from the stereo pairs are shown below.  I would be grateful for any further information on the scenes