Henri Plait opened in 1910 his first photography store at Rue Lafayette 37 in Paris. After the outbreak of the First World War he was mobilised by the French army. He became ill and suffered from pleurisy. He was dismissed from military service after his recovery[1].

He returned to his store and started promoting a camera especially for the soldiers at the front. He marketed the Vest Pocket Kodak, a compact folding camera that used film and was easy to carry. The marketing slogan was Le Kodak du Soldat (The soldier’s Kodak)[2].
He offered services to the soldiers at the front. They could send their negatives by post. Photo-Plait developed the negatives and sent the printed images back to the photographer.

Photo-Plait expanded its business activities after the war and opened more stores in Paris. He started publishing the magazine La Photo Pour Tous (“Photo For Everyone”)[1]. The first edition was published in 1923 and the magazine appeared until the outbreak of the Second World War. The richly illustrated magazine had 20 pages and was published monthly to subscribers. It covered both photography and cinema.
After a long history, the last Photo-Plait store closed its doors in the 1970s[1].
Selling stereoviews
The Photo-Plait catalog of 1918–1919[3] contains a detailed list of 14 series of 12 glass stereoviews with their number and title. The slides are manufactured by La Stéréoscopie Universelle and have numbers in the 3200, 7000, 8300 and 8400 ranges. The catalog establishes the link between stereoview manufacturer and seller.

The catalog was published in June 1918. The war still raged and this explains the statement:
Éditions autorisée par le Ministère de la Guerre
(authorized by the Ministry of War)
The catalog of 1919[4] contains 100 series of 12 slides, but now it only mentions the name of the series because Photo-Plait refers to special catalogs for the war stereoviews.

References
- Halgand, Sylvain. Photo-Plait : une petite histoire de la photographie française, April 2011 – via collection-appareils.fr
- Photo-Plait Catalogue Général, April 1916, p.15
- Photo-Plait 1918-1919, Photo-Plait, June 1918, p.147
- Photo-Plait Catalogue Général, Autumn 1919, p.158