This rear shot illustrates the older type of framework to accommodate two one man hose carts - a French innovation which is still to be found on pump appliances (except for brush trucks) all over France.
Somua was founded in 1914 to build military equipment for the French army, including artillery and the original (and very effective) French light tanks. They famously built tanks in WWII too, and continued to build specialty military vehicles up to 1955, when the business folded. Their fire appliance business was started just after WWI, supplying units like this example to Paris, which of course had a fire service which was a battalion of the French army's engineering corps. They continued to build fire appliances up to the early 1950s, building units for various SDIS as well as the RSPP.
Added by Rob Johnson on 01 April 2021.